Large-diameter variable-diameter single-pile longitudinal-seam welding protective structure, cylinder longitudinal-seam welding device and corresponding welding method

Abstract

The present application relates to the technical fields of welding, and discloses a large-diameter variable-diameter single-pile longitudinal-seam welding protection structure, a cylinder longitudinal-seam welding device and a corresponding welding method, both ends of a bottom placing frame are fixed with vertical seats, a lifting seat assembly is slidably connected to the vertical seats, and the lifting seat assembly moves up and down under the drive of a jacking hydraulic cylinder in the bottom of the vertical seat; a ejection disc driven by an ejection hydraulic cylinder is arranged at the inner side end of the lifting seat assembly, a top-width plate for being inserted into a welding longitudinal seam on a single-pile cylinder is arranged on the ejection disc, opening and closing seats are slidably connected in the equally spaced sliding grooves on the ejection disc, a rectangular frame is connected to the opening and closing seats at one end through a push-pull arm, and rubber clamping rollers are arranged on the U-shaped seats at the other end of the opening and closing seats. The top-width plate of the present application is inserted into the welding longitudinal seam to support and shape, and offsets the welding shrinkage stress; multiple groups of rubber clamping rollers synchronously clamp the outer wall of the single-pile cylinder, limit the radial shaking and deviation of the cylinder, and have obvious protection effect, and double limiting from inside and outside, which greatly improves the welding forming quality.

Description

Technical Field

[0001] This invention relates to the field of welding technology, specifically to a large-diameter variable-diameter single-pile longitudinal seam welding protection structure, a cylindrical longitudinal seam welding device, and a corresponding welding method. Background Technology

[0002] Currently, longitudinal seam welding of large-diameter variable-diameter monopile cylinders commonly suffers from welding deformation and poor positioning stability. Traditional welding fixtures lack dedicated weld seam shaping and external wall linkage clamping structures, making them unsuitable for continuous welding operations of variable-diameter monopile cylinders. Radial displacement and swaying easily occur during cylinder welding, severely impacting longitudinal seam welding quality and operational efficiency. The welded longitudinal seam is prone to shrinkage under high-temperature stress, resulting in uneven bevel width and poor weld formation accuracy. Furthermore, traditional equipment often employs multi-cylinder independent drive clamping and positioning structures, leading to poor synchronization of actions, cumbersome structures, and high equipment costs. Therefore, we have introduced a protective structure for longitudinal seam welding of large-diameter variable-diameter monopile cylinders, a longitudinal seam welding device for cylinders, and a corresponding welding method. Summary of the Invention

[0003] The purpose of this invention is to provide a large-diameter variable-diameter single pile longitudinal seam welding protection structure, a cylinder longitudinal seam welding device and a corresponding welding method to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a longitudinal seam welding protection structure for a large-diameter variable-diameter single pile, including a bottom placement frame for placing the single pile cylinder, with uprights fixed at both ends of the bottom placement frame, and a lifting seat assembly slidably connected on the uprights, the lifting seat assembly moving up and down under the drive of a lifting hydraulic cylinder inside the bottom of the uprights; The inner end of the lifting seat assembly is provided with an ejection plate driven by an ejection hydraulic cylinder. The ejection plate is provided with a top width plate for insertion into the welded longitudinal seam on the single pile cylinder. An opening and closing seat is slidably connected in the sliding grooves evenly distributed on the ejection plate. One end of the opening and closing seat is connected to a rectangular frame by a push-pull arm, and a rubber clamping roller is provided on the U-shaped seat at the other end of the opening and closing seat. An ejector column is provided at the center of the outer end of the ejector plate. A rotating arm is mounted on the ejector column by a fixed shaft. A connecting lug is fixed to the inner wall of the limiting cylinder of the lifting seat assembly. One end of the rotating arm is slidably connected to the inclined groove on the connecting ear by a first pin, and the other end of the rotating arm is slidably connected to the rectangular frame by a second pin.

[0005] Preferably, the bottom placement frame includes a bottom frame and placement rollers symmetrically arranged on the bottom frame.

[0006] Preferably, the lifting seat assembly includes a U-shaped slide block slidably connected to the upright seat and a limiting box disposed on the outer end of the U-shaped slide block, wherein the limiting box is fixed between the U-shaped slide blocks; The ejection hydraulic cylinder is fixed to the outer end of the limiting box, and the ejection piston rod of the output end of the ejection hydraulic cylinder extends into the limiting box and is connected to the limiting seat. The limiting seat slides into the limiting box, and the ejection column extends into the limiting box and is fixed to the limiting seat.

[0007] Preferably, the lifting piston rod at the output end of the lifting hydraulic cylinder is connected to the bottom of the limiting cylinder.

[0008] Preferably, the ejector column is provided with a mounting ear plate, and the rotating arm is rotatably connected to the mounting ear plate by a fixed shaft.

[0009] A cylindrical longitudinal seam welding device includes the aforementioned large-diameter variable-diameter single-pile longitudinal seam welding protection structure, and further includes a guide rail fixed at the rear end of a bottom placement frame and a movable seat slidably connected to the guide rail. A horizontal moving hydraulic cylinder is installed on the movable seat, and the output end of the horizontal moving hydraulic cylinder passes through the movable seat and is connected to a horizontal mounting seat. A lifting moving hydraulic cylinder is provided at the upper end of the horizontal mounting seat, and the output end of the lifting moving hydraulic cylinder passes through the horizontal mounting seat and is connected to a lifting mounting seat. A welding gun head is provided at the bottom of the lifting mounting seat.

[0010] The present invention also provides a welding method for a cylindrical longitudinal seam welding device, specifically including the following steps: S1. Place the single pile cylinder on the bottom placement frame; S2. The ejector hydraulic cylinder drives the ejector plate to approach the end of the single pile cylinder. At the same time, the rotating arm pulls the opening and closing seat at the end of the push-pull arm to slide along the slide groove until the rubber clamping roller clamps the outer wall of the end of the single pile cylinder and the top width plate is inserted into the welded longitudinal seam on the single pile cylinder. S3. The welding torch head is used to weld the longitudinal seam.

[0011] Compared with the prior art, the beneficial effects of the present invention are: This invention inserts a top-width plate into the longitudinal weld seam to expand and shape it, offsetting welding shrinkage stress. Multiple sets of rubber clamping rollers simultaneously clamp the outer wall of the single pile cylinder, limiting radial sway and displacement of the cylinder, resulting in significant protection. Furthermore, the dual internal and external limiting significantly improves the quality of welding formation. Moreover, this invention is driven solely by an ejector hydraulic cylinder, in conjunction with a rotating arm, inclined groove, and push-pull arm linkage structure, to simultaneously complete the clamping of the expansion seam and the outer wall. This eliminates the need for multiple drives, resulting in a compact structure, synchronized and precise movements, and reduced equipment costs and energy consumption. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the structure of the single pile cylinder after placement according to the present invention; Figure 2 This is a schematic diagram of the structure connecting the bottom frame, movable base, upright base, and top plate of the present invention; Figure 3 This is a schematic diagram of the structure connecting the bottom frame, the upright, the lifting seat assembly, and the top plate of the present invention; Figure 4 This is a three-dimensional structural diagram of the welding longitudinal seam according to the present invention; Figure 5 This is a schematic diagram of the initial state structure of the connection between the ejector plate, the lifting seat assembly, and the lifting hydraulic cylinder of the present invention. Figure 6 For the present invention Figure 5 A structural diagram from another perspective; Figure 7 For the present invention Figure 6 A schematic diagram of the cross-sectional structure; Figure 8 This is a schematic diagram of the structure of the connecting ear and the limiting cylinder of the present invention; Figure 9 This is a schematic diagram of the connection between the ejector plate, push-pull arm, rotating arm and ejector column of the present invention; Figure 10 This is a schematic diagram of the structure of the single pile cylinder after clamping and fixing according to the present invention; Figure 11 This is a schematic diagram of the structure of the present invention when the rubber clamping roller is closed and clamps the outer wall of a single pile cylinder. Figure 12 For the present invention Figure 11 A cross-sectional structural diagram.

[0013] In the diagram: 1. Bottom frame; 2. Single pile cylinder; 3. Placement roller; 4. Stand; 5. Ejection plate; 6. Limit box; 7. Ejection hydraulic cylinder; 8. U-shaped slide; 9. Limit cylinder; 10. Moving seat; 11. Horizontal moving hydraulic cylinder; 12. Lifting moving hydraulic cylinder; 13. Horizontal mounting seat; 14. Lifting mounting seat; 15. Welding gun head; 16. Top width plate; 17. Rubber clamping roller; 18. Lifting hydraulic cylinder; 19. Lifting piston rod; 20. Guide rail; 21. Welded longitudinal seam; 22. Slide groove; 23. Opening and closing seat; 24. U-shaped seat; 25. Push-pull arm; 26. Ejection column; 27. Ejection piston rod; 28. Limit seat; 29. ​​Connecting ear; 30. Inclined groove; 31. First pin; 32. Rotating arm; 33. Second pin; 34. Rectangular frame; 35. Fixed shaft; 36. Mounting ear plate. Detailed Implementation

[0014] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0015] Example: Please see Figures 1-12The present invention provides a technical solution: A protective structure for longitudinal seam welding of a large-diameter variable-diameter monopile includes a bottom placement frame for placing the monopile cylinder 2. The two ends of the bottom placement frame are fixed with a base 4. A lifting seat assembly is slidably connected to the base 4. The lifting seat assembly moves up and down under the drive of a lifting hydraulic cylinder 18 inside the bottom of the base 4. The inner end of the lifting seat assembly is provided with an ejection plate 5 driven by an ejection hydraulic cylinder 7. The ejection plate 5 is provided with a top width plate 16 for insertion into the longitudinal seam 21 of the monopile cylinder 2. An opening and closing seat 23 is slidably connected in the grooves 22 evenly distributed on the ejection plate 5. One end of the opening and closing seat 23 is connected to a rectangular frame 34 by a push-pull arm 25. A rubber clamping roller 17 is provided on the U-shaped seat 24 at the other end of the opening and closing seat 23.

[0016] An ejector post 26 is provided at the center of the outer side of the ejector plate 5. A rotating arm 32 is mounted on the ejector post 26 by means of a fixed shaft 35. A connecting ear 29 is fixed on the inner wall of the limiting cylinder 9 of the lifting seat assembly. One end of the rotating arm 32 is slidably connected to the inclined groove 30 on the connecting ear 29 by means of a first pin 31. The other end of the rotating arm 32 is slidably connected to the rectangular frame 34 by means of a second pin 33.

[0017] The bottom placement frame includes a bottom frame 1 and placement rollers 3 symmetrically arranged on the bottom frame 1.

[0018] The lifting seat assembly includes a U-shaped slide 8 that slides within the upright seat 4 and a limiting box 6 located at the outer end of the U-shaped slide 8. A limiting cylinder 9 is fixed between the U-shaped slides 8. An ejection hydraulic cylinder 7 is fixed at the outer end of the limiting box 6, and the ejection piston rod 27 at the output end of the ejection hydraulic cylinder 7 extends into the limiting box 6 and is connected to a limiting seat 28. The limiting seat 28 slides within the limiting box 6, and the ejection column 26 extends into the limiting box 6 and is fixed to the limiting seat 28.

[0019] The lifting piston rod 19 at the output end of the lifting hydraulic cylinder 18 is connected to the bottom of the limiting cylinder 9. The ejector column 26 is provided with a mounting ear plate 36, and the rotating arm 32 is rotatably connected to the mounting ear plate 36 by a fixed shaft 35.

[0020] A cylindrical longitudinal seam welding device includes a large-diameter variable-diameter single-pile longitudinal seam welding protection structure, and a guide rail 20 fixed at the rear end of the bottom placement frame and a movable seat 10 slidably connected to the guide rail 20. A horizontal moving hydraulic cylinder 11 is installed on the movable seat 10. The output end of the horizontal moving hydraulic cylinder 11 passes through the movable seat 10 and is connected to a horizontal mounting seat 13. A lifting moving hydraulic cylinder 12 is provided at the upper end of the horizontal mounting seat 13. The output end of the lifting moving hydraulic cylinder 12 passes through the horizontal mounting seat 13 and is connected to a lifting mounting seat 14. A welding gun head 15 is provided at the bottom of the lifting mounting seat 14.

[0021] The present invention also provides a welding method for a cylindrical longitudinal seam welding device, specifically including the following steps: S1. Place the single pile cylinder 2 on the bottom placement frame; S2. The ejector hydraulic cylinder 7 drives the ejector plate 5 to approach the end of the single pile cylinder 2. At the same time, the rotating arm 32 pulls the opening and closing seat 23 at the end of the push-pull arm 25 to slide along the slide groove 22 until the rubber clamping roller 17 clamps the outer wall of the end of the single pile cylinder 2 and the top width plate 16 is inserted into the welded longitudinal seam 21 on the single pile cylinder 2. S3, Welding gun head 15 welds the longitudinal seam 21.

[0022] Specifically, when using it: This invention consists of two main core parts: First, a longitudinal weld protection structure for large-diameter variable-diameter single piles is used to open and shape the longitudinal weld 21 of the large-diameter variable-diameter single pile cylinder 2, and to clamp and limit it on the outer wall to avoid weld shrinkage and deformation and cylinder displacement during the welding process. Second, the longitudinal seam welding actuator for the cylinder, equipped with a welding torch 15, completes automated longitudinal seam welding. All actions rely on hydraulic cylinder linkage to achieve synchronous positioning, seam support, and outer wall clamping. Each structure is marked with a corresponding number. The overall working principle is explained in the following sections: placement and positioning, synchronous seam support and clamping of the protective structure, and welding feed. I. Working principle of integral load-bearing foundation structure: The bottom placement frame consists of a bottom frame 1 and placement rollers 3 symmetrically arranged on the bottom frame 1. The placement rollers 3 support the single pile cylinder 2 and can be adapted to single pile cylinders 2 with large diameter and variable diameter specifications. The cylinder can be rotated and adjusted slightly on the placement rollers 3 to facilitate alignment with the welding longitudinal seam 21, providing basic bearing support for subsequent clamping, seam support and welding.

[0023] The bottom frame 1 is fixedly mounted on the two ends of the support base 4. The lifting hydraulic cylinder 18 is installed inside the support base 4. The lifting piston rod 19 at the output end of the lifting hydraulic cylinder 18 is connected upward to the bottom of the limiting cylinder 9. The lifting seat assembly is slidably assembled inside the upright 4. The lifting seat assembly includes a U-shaped slide 8, a limit box 6, and a limit cylinder 9. The lifting hydraulic cylinder 18 pushes and pulls the limit cylinder 9 through the lifting piston rod 19, causing the U-shaped slide 8 to slide vertically along the upright 4, thereby realizing the overall lifting of the entire lifting seat assembly. It can adapt to single pile cylinders 2 with different diameters and different height positions, and meet the adaptation requirements of variable diameter single piles.

[0024] II. Working principle of the ejection feed and linkage transmission mechanism: The ejector hydraulic cylinder 7 is fixed on the outside of the limit box 6. The ejector piston rod 27 at its output end extends into the limit box 6 and connects to the limit seat 28. The limit seat 28 is slidably assembled in the inner cavity of the limit box. One end of the ejector column 26 extends into the limit box 6 and is rigidly fixed to the limit seat 28. The other end extends outward and is assembled with the ejector plate 5.

[0025] When the ejector hydraulic cylinder 7 extends, the ejector piston rod 27 pushes the limit seat 28 to slide forward, and simultaneously drives the ejector column 26, the ejector plate 5 and the rubber clamping roller 17 installed on the ejector plate 5 to be fed horizontally to the end of the single pile cylinder 2, so that the ejector plate 5 is close to the end face of the cylinder.

[0026] An mounting ear plate 36 is provided on the outer side of the ejector column 26, and the fixed shaft 35 rotatably hinges the rotating arm 32 to the mounting ear plate 36; the inner wall of the limiting cylinder 9 fixed between the U-shaped slides 8 is provided with a connecting ear 29, and the connecting ear 29 has an inclined groove 30. The first pin 31 at one end of the rotating arm 32 slides into the inclined groove 30, and the second pin 33 at the other end of the rotating arm 32 slides in cooperation with the rectangular frame 34.

[0027] The ejector plate 5 has equally spaced grooves 22, and the opening and closing seat 23 is slidably assembled in the grooves 22. One end of the opening and closing seat 23 is connected to the rectangular frame 34 through the push-pull arm 25, and the other end of the opening and closing seat 23 is provided with a U-shaped seat 24, on which a rubber clamping roller 17 is assembled.

[0028] When the ejector hydraulic cylinder 7 pushes the ejector column 26 forward and the ejector plate 5 moves forward as a whole, the first pin 31 slides relative to the inclined groove 30 of the connecting lug 29, and the inclined surface of the inclined groove 30 constrains and drives the rotating arm 32 to rotate with the fixed shaft 35 as the fulcrum. During the rotation of the rotating arm 32, the rectangular frame 34 is pulled synchronously towards the center of the ejector plate 5 via the second pin 33. The rectangular frame 34 is pulled by the push-pull arm 25 to move multiple sets of opening and closing seats 23 synchronously along the slide groove 22 towards the center. Finally, all the rubber clamping rollers 17 are synchronously pressed against the outer wall of the end of the single pile cylinder 2. Such pressing and clamping can prevent the longitudinal weld seam 21 on the single pile cylinder 2 from expanding, and the end of the single pile cylinder 2 is synchronously clamped and limited to prevent the single pile cylinder 2 from swaying or shifting radially during welding, thus playing a protective role.

[0029] III. Working principle of weld seam expansion and shaping structure: A top width plate 16 is provided on the end face of the ejector plate 5 facing the single pile cylinder 2. Under the synchronous action of the ejector hydraulic cylinder 7 pushing the ejector plate 5 to feed and the rubber clamping roller 17 clamping the outer wall of the cylinder, the top width plate 16 is inserted into the welded longitudinal seam 21 of the single pile cylinder 2. The top width plate 16 provides support for the longitudinal weld 21, helping to open, shape, and define its width. This counteracts the shrinkage stress caused by the high temperature of welding, prevents the longitudinal weld 21 from shrinking inward during the welding process, ensures a uniform bevel width for the longitudinal weld 21, and improves the quality of the weld formation. The rubber clamping roller 17 flexibly contacts the outer wall of the single pile cylinder 2, and will not scratch the outer surface of the single pile cylinder 2 during the clamping process.

[0030] IV. Working principle of the longitudinal seam welding actuator for the cylinder: The longitudinal seam welding device for the cylinder body is supplemented with a welding walking and welding unit based on the above-mentioned welding protection structure: a guide rail 20 is fixed at the rear end of the bottom placement frame, and a movable seat 10 is slidably mounted on the guide rail 20; a horizontal moving hydraulic cylinder 11 is installed on the movable seat 10, and the output end of the horizontal moving hydraulic cylinder 11 passes through the movable seat 10 and connects to the horizontal mounting seat 13. By relying on the extension and retraction of the horizontal moving hydraulic cylinder 11, the horizontal mounting seat 13 is driven to adjust horizontally in the direction perpendicular to the longitudinal seam 21 of the welding body, so as to adapt to the transverse position of the weld seam of different cylinder diameters.

[0031] A lifting and moving hydraulic cylinder 12 is mounted on the upper end of the horizontal mounting base 13. The output end of the lifting and moving hydraulic cylinder 12 passes through the horizontal mounting base 13 and is connected to the lifting mounting base 14. The lifting and moving hydraulic cylinder 12 can drive the lifting mounting base 14 to move up and down, and adjust the vertical distance between the welding gun head 15 and the welding longitudinal seam 21. The bottom of the lifting mounting base 14 is fixed with the welding gun head 15, enabling multi-dimensional position adjustment of the welding actuator. During welding operations, the moving base 10 moves longitudinally along the guide rail 20, driving the welding gun head 15 to move at a constant speed along the entire weld seam 21, thus achieving continuous longitudinal weld seam welding operations.

[0032] V. Working principle of the complete welding process of the whole set of equipment: Process S1: Cylinder Placement and Positioning. The single pile cylinder 2 to be welded is hoisted and placed on the placement roller 3 above the bottom frame 1. The placement roller 3 supports the cylinder. The cylinder can be manually rotated so that the longitudinal seam 21 to be welded faces the welding gun head 15, thus completing the pre-foundation positioning. According to the diameter specification of the single pile cylinder 2, the lifting hydraulic cylinder 18 can be started, and the lifting seat assembly can be driven to rise and fall as a whole through the lifting piston rod 19, adjusting the height of the ejector plate 5 to match the height of the cylinder end face.

[0033] Process S2: Synchronous support joint + outer wall clamping protection forming start the ejection hydraulic cylinder 7, the ejection piston rod 27 pushes the limit seat 28 forward, driving the ejection column 26 and ejection plate 5 to extend horizontally to the end of the single pile cylinder 2; two sets of linkage actions occur simultaneously: ① The rotating arm 32 moves forward with the ejection column 26, the first pin 31 slides along the inclined groove 30 to drive the rotating arm 32 to deflect, and the second pin 33 pulls the rectangular frame 34 to close, and through the push-pull arm 25 drives all the opening and closing seats 23 to slide along the sliding groove 22 towards the center, and the rubber clamping roller 17 clamps the outer wall of the end of the single pile cylinder 2 simultaneously to achieve circumferential positioning of the cylinder; ② The ejection plate 5 moves forward synchronously with the feed, and the top width plate 16 is directly inserted into the interior of the welded longitudinal seam 21 to open and shape the weld, offset the welding shrinkage deformation, and complete the weld protection positioning.

[0034] Process S3: Automated longitudinal seam welding operation. Adjust the horizontal moving hydraulic cylinder 11 and the lifting moving hydraulic cylinder 12 to adjust the horizontal and vertical heights of the welding gun head 15 so that the welding gun head 15 is aligned with the bevel of the longitudinal seam 21 after it has been opened. The moving seat 10 moves at a uniform speed along the longitudinal direction of the guide rail 20, and the welding gun head 15 continuously welds the longitudinal seam 21. Throughout the welding process, the rubber clamping roller 17 continuously clamps the end of the single pile cylinder 2 and the top width plate 16 continuously supports the weld, always restraining the deformation of the single pile cylinder 2 and the weld until the entire longitudinal seam 21 is welded.

[0035] VI. Summary of the core synergy advantage principle: Single-cylinder synchronous linkage: The two sets of protective actions, namely the weld width fixation and the circumferential clamping of the outer wall of the single pile cylinder 2, are completed synchronously by a single ejection hydraulic cylinder 7. The synchronous action is achieved by the inclined plane linkage transmission mechanism composed of rotating arm 32, inclined groove 30, rectangular frame 34 and push-pull arm 25. No multiple independent drives are required. The structure is compact and the action synchronization is high. Variable diameter adaptation capability: The lifting hydraulic cylinder 18 drives the entire lifting seat assembly to lift and lower, and the placement roller 3 can rotate to support the single pile cylinder 2, which can adapt to single pile cylinders 2 with different diameters and variable diameter structures. Double protection against welding deformation: Rubber clamping roller 17 restricts the radial displacement of the single pile cylinder 2, and the top width plate 16 has built-in support to open the longitudinal weld seam 21. The welding thermal deformation is constrained from both the outside of the single pile cylinder 2 and the inside of the weld seam, ensuring the welding forming accuracy of the longitudinal seam. Multi-dimensional adjustable welding mechanism: horizontal moving hydraulic cylinder 11, lifting moving hydraulic cylinder 12, guide rail 20 and moving seat 10, realize three-dimensional position adjustment of welding gun head 15, which can match the automated continuous welding of longitudinal seams of single piles of different specifications.

[0036] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A cylindrical longitudinal seam welding device, comprising a large-diameter variable-diameter single-pile longitudinal seam welding protection structure, characterized in that: The large-diameter variable-diameter single pile longitudinal seam welding protection structure includes a bottom placement frame for placing the single pile cylinder, with uprights fixed at both ends of the bottom placement frame, and a lifting seat assembly slidably connected on the uprights. The lifting seat assembly moves up and down under the drive of a lifting hydraulic cylinder inside the bottom of the uprights. The inner end of the lifting seat assembly is provided with an ejection plate driven by an ejection hydraulic cylinder. The ejection plate is provided with a top width plate for insertion into the welded longitudinal seam on the single pile cylinder. An opening and closing seat is slidably connected in the sliding grooves evenly distributed on the ejection plate. One end of the opening and closing seat is connected to a rectangular frame by a push-pull arm, and a rubber clamping roller is provided on the U-shaped seat at the other end of the opening and closing seat. An ejector column is provided at the center of the outer end of the ejector plate. A rotating arm is mounted on the ejector column by a fixed shaft. A connecting lug is fixed to the inner wall of the limiting cylinder of the lifting seat assembly. One end of the rotating arm is slidably connected to the inclined groove on the connecting ear by a first pin, and the other end of the rotating arm is slidably connected to the rectangular frame by a second pin. The lifting seat assembly includes a U-shaped slide block slidably connected to the upright seat and a limiting box provided at the outer end of the U-shaped slide block, wherein the limiting box is fixed between the U-shaped slide blocks; The ejection hydraulic cylinder is fixed to the outer end of the limit box, and the ejection piston rod of the output end of the ejection hydraulic cylinder extends into the limit box and is connected to the limit seat. The limit seat slides in the limit box, and the ejection column extends into the limit box and is fixed to the limit seat. The lifting piston rod at the output end of the lifting hydraulic cylinder is connected to the bottom of the limiting cylinder; The ejector column is provided with a mounting ear plate, and the rotating arm is rotatably connected to the mounting ear plate by a fixed shaft; the bottom placement frame includes a bottom frame and placement rollers symmetrically arranged on the left and right sides of the bottom frame. The bottom placement frame has a guide rail fixed at the rear end and a movable seat that slides on the guide rail. A horizontal moving hydraulic cylinder is installed on the movable seat. The output end of the horizontal moving hydraulic cylinder passes through the movable seat and is connected to a horizontal mounting seat. A lifting moving hydraulic cylinder is provided at the upper end of the horizontal mounting seat. The output end of the lifting moving hydraulic cylinder passes through the horizontal mounting seat and is connected to a lifting mounting seat. A welding gun head is provided at the bottom of the lifting mounting seat.

2. A welding method for the cylindrical longitudinal seam welding device according to claim 1, characterized in that: Specifically, the following steps are included: S1. Place the single pile cylinder on the bottom placement frame; S2. The ejector hydraulic cylinder drives the ejector plate to approach the end of the single pile cylinder. At the same time, the rotating arm pulls the opening and closing seat at the end of the push-pull arm to slide along the slide groove until the rubber clamping roller clamps the outer wall of the end of the single pile cylinder and the top width plate is inserted into the welded longitudinal seam on the single pile cylinder. S3. The welding torch head is used to weld the longitudinal seam.

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