Metal pipeline welding device for water conservancy construction and welding method thereof

Abstract

The invention belongs to the technical field of metal pipeline welding, and particularly relates to a metal pipeline welding device for water conservancy construction, which comprises a bottom plate, a first pipeline fastener and a second pipeline fastener which are distributed left and right are arranged above the bottom plate, and a welding mechanism is arranged between the first pipeline fastener and the second pipeline fastener; a welding method of the metal pipeline welding device for water conservancy construction is characterized by comprising the following steps that S1, a construction trench is excavated in the welding end of an original metal pipeline in advance, a bottom plate is laid in the construction trench and fixed through mud nails, and then the original metal pipeline is fixedly sleeved with a first pipeline fastener; welding work of the metal pipelines can be automatically completed, welding seams between the pipelines are stable in the welding process, and the welding effect is guaranteed while the welding efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of metal pipeline welding, and particularly relates to a metal pipeline welding device for water conservancy construction and a welding method thereof. Background Art

[0002] A water conservancy project is a project built for controlling and allocating surface water and groundwater in nature to achieve the purpose of eliminating disasters and bringing benefits. Only by building a water conservancy project can the water flow be controlled, flood disasters be prevented, and the regulation and distribution of water volume be carried out to meet the needs of people's life and production for water resources. A water conservancy project needs to build different types of hydraulic structures such as dams, dikes, spillways, sluice gates, water inlets, channels, aqueducts, raft channels, fishways, etc. to achieve its goals. During the water conservancy construction process, it is usually necessary to lay and weld metal pipelines to ensure the connection between multiple sections of metal pipelines.

[0003] However, during water conservancy construction, metal pipelines are laid section by section. After each section of the pipeline is laid, its position cannot be moved. Subsequently, when welding and connecting the next section of the pipeline, a crane device is required to lift the pipeline to an appropriate height, and then the welding end faces need to be stacked by manual pushing before manual welding work can be carried out. This working method not only consumes a lot of manpower, but also has a low welding accuracy and cannot ensure the stability of the weld during the welding process.

[0004] To solve the above problems, we propose a metal pipeline welding device for water conservancy construction and a welding method thereof. Summary of the Invention

[0005] The purpose of the present invention is to solve the problems in the background art, and a metal pipeline welding device for water conservancy construction is proposed.

[0006] To achieve the above purpose, the present invention adopts the following technical solution: a metal pipeline welding device for water conservancy construction and a welding method thereof, including a bottom plate. Above the bottom plate, there are a first pipeline fastener and a second pipeline fastener distributed left and right. A welding mechanism is arranged between the first pipeline fastener and the second pipeline fastener. Both the lower ends of the first pipeline fastener and the second pipeline fastener are fixedly connected with mounting plates. Four telescopic rods distributed in a rectangle are fixedly connected to the lower end of the mounting plate on the left side. A moving mechanism is arranged on the upper end of the bottom plate and below the mounting plate on the right side. The moving mechanism is connected to the mounting plate on the right side through a lifting member. The first pipeline fastener is firmly connected to the original metal pipeline, and the second pipeline fastener is firmly connected to the new metal pipeline. The lifting mechanism is used to adjust the position height of the new metal pipeline to make it consistent with the height of the original metal pipeline, so as to move its welding end to coincide with the welding end of the original metal pipeline by using the moving mechanism.

[0007] In the above-mentioned metal pipe welding device and its welding method for water conservancy construction, four socket sleeves distributed in a rectangle are fixedly connected to the upper end of the bottom plate, and the telescopic ends of the four telescopic rods are inserted into the corresponding socket sleeves respectively.

[0008] In the above-mentioned metal pipe welding device for water conservancy construction, the moving mechanism includes two vertical plates fixedly connected to the bottom plate and distributed left and right. A first threaded rod and a guide rod are arranged between the two vertical plates. The first threaded rod is rotatably connected to the two vertical plates, and the guide rod is fixedly connected to the two vertical plates. A first motor for driving the first threaded rod to rotate is fixedly installed on the right vertical plate. A sleeve plate is sleeved on the first threaded rod and the guide rod together. The sleeve plate is threadedly connected to the first threaded rod and slidably connected to the guide rod. A moving plate is fixedly connected to the upper end of the sleeve plate, and four moving wheels that are in rolling contact with the bottom plate are installed at the lower end of the moving plate.

[0009] In the above-mentioned metal pipe welding device for water conservancy construction, four fixing blocks distributed in a rectangle are fixedly connected to the upper end of the moving plate and the lower end of the right installation plate respectively. A second threaded rod is rotatably connected between the two fixing blocks on the moving plate and located on the right side. A downward sliding rod is fixedly connected between the two fixing blocks on the moving plate and located on the left side. An upward sliding rod is fixedly connected between every two front and rear corresponding fixing blocks at the lower end of the installation plate. The lifting member includes two cross-activity rods arranged coaxially. The rear ends of the two cross-activity rods are respectively rotatably connected to the four fixing blocks at the rear side. The front ends of the two cross-activity rods are both rotatably connected with moving sleeve blocks. The four moving sleeve blocks are respectively sleeved on the second threaded rod, the downward sliding rod and the upward sliding rod. The moving sleeve blocks are threadedly connected to the second threaded rod and slidably connected to the downward sliding rod and the upward sliding rod. A connecting rod is fixedly connected between every two left and right corresponding moving sleeve blocks. A second motor for driving the second threaded rod to rotate is fixedly installed on one of the fixing blocks.

[0010] In the above-mentioned metal pipe welding device for water conservancy construction, the welding mechanism includes a positioning ring sleeved on the new metal pipe. The positioning ring is composed of two semi-circular frames arranged up and down relatively. The two semi-circular frames are connected by bolts. Semi-circular sliding grooves are opened on the outer arc surfaces of the two semi-circular frames. The two semi-circular sliding grooves communicate with each other to form an annular sliding groove. A sliding block is slidably connected in the annular sliding groove. One end of the sliding block located outside the annular sliding groove is fixedly installed with an electric trolley. The wheels of the electric trolley are in rolling contact with the outer peripheral surface of the positioning ring. A welding torch is installed on the electric trolley. Two positioning and clamping mechanisms are arranged on the inner arc surfaces of the two semi-circular frames respectively. The four positioning and clamping mechanisms are evenly distributed circumferentially.

[0011] In the above-mentioned metal pipe welding device for water conservancy construction, the positioning and clamping mechanism includes two end plates fixedly connected to the inner wall of the semi-circular frame and distributed at intervals left and right. A bidirectional threaded rod is rotatably connected between the two end plates. Two symmetrically arranged threaded sleeve blocks are threadedly sleeved on the bidirectional threaded rod. An active connecting rod is rotatably connected to each of the two threaded sleeve blocks. The ends of the two active connecting rods away from the threaded sleeve blocks are rotatably connected to a contact block. Limiting grooves are horizontally opened on the inner wall of the semi-circular frame at positions corresponding to the threaded sleeve blocks. A limiting block is slidably connected in each limiting groove. The end of the limiting block away from the limiting groove is fixedly connected to the corresponding threaded sleeve block. One end of the bidirectional threaded rod penetrates the end plate and is coaxially fixedly connected to a rotating block.

[0012] A welding method for a metal pipe welding device for water conservancy construction is characterized by the following steps: S1. First, dig a construction pit at the welding end of the original metal pipe, lay the bottom plate in the construction pit, and fix it with mud nails. Then, fixedly sleeve the first pipe fastener on the original metal pipe, and insert the four telescopic rods below into the four socket sleeves correspondingly. Then, fixedly sleeve the second pipe fastener on the new metal pipe; S2. Assemble the two semi-circular frames at the position of the new metal pipe close to the welding end to form a positioning ring. By rotating each rotating block, make the four contact blocks abut against the outer wall of the new metal pipe, so that the positioning ring is concentric with the new metal pipe. During the assembly process, slide the sliding block into the semi-circular sliding groove, and then complete the installation work of the electric trolley and the welding torch; S3. Drive the lifting member to work through the second motor to drive the new metal pipe to lift, so that the new metal pipe moves to the same height as the original metal pipe. Then, drive the first threaded rod to rotate through the first motor, and use the moving mechanism to drive the new metal pipe to move towards the original metal pipe until the welding ends of the two coincide, so that the formed weld seam remains in a stable state; S4. Adjust the welding torch so that its welding head is aligned with the weld seam. Then, drive the welding torch to make a circular motion by moving the electric trolley along the circular sliding groove, that is, complete the welding work of the two metal pipes; S5. After welding is completed, disassemble and remove the first pipe fastener, the second pipe fastener, the positioning ring and the bottom plate, and then the welding work of the next section of metal pipe can be carried out.

[0013] Compared with the existing technology, the advantages of the present invention are as follows: 1. By setting the first pipe fastener and the second pipe fastener, the original metal pipe and the new metal pipe can be easily connected to the device. Then, only by using the moving mechanism and the lifting member, the movement of the new metal pipe can be controlled to make it at the same height as the original metal pipe and make the welding points of the two coincide to keep the weld seam stable.

[0014] 2. By setting up a welding mechanism, the welding mechanism can be assembled on the new metal pipeline through two semi-circular frames, and thus move to the welding position along with the new metal pipeline. The electric trolley makes a circular motion on the positioning ring formed by the semi-circular frames, so as to control the welding torch to make a circular motion around the positioning ring. Furthermore, the welding work of the circular weld of the metal pipeline can be carried out without rotating the metal pipeline. The welding work is carried out automatically without manual welding. The whole welding work does not require a large amount of manpower, greatly improving the welding efficiency and saving labor costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a perspective view of a metal pipeline welding device for water conservancy construction proposed by the present invention; Figure 2 is a partial structure perspective view of a metal pipeline welding device for water conservancy construction proposed by the present invention; Figure 3 is a perspective view of the bottom plate in a metal pipeline welding device for water conservancy construction proposed by the present invention; Figure 4 is a perspective view of the moving mechanism in a metal pipeline welding device for water conservancy construction proposed by the present invention; Figure 5 is a perspective view of the welding mechanism in a metal pipeline welding device for water conservancy construction proposed by the present invention; Figure 6 is a partial structure perspective view of the welding mechanism in a metal pipeline welding device for water conservancy construction proposed by the present invention; Figure 7 is a perspective view of the electric trolley in a metal pipeline welding device for water conservancy construction proposed by the present invention; Figure 8 is a perspective view of the positioning and clamping mechanism in a metal pipeline welding device for water conservancy construction proposed by the present invention.

[0016] In the figure: 1 bottom plate, 2 first pipeline fastener, 3 second pipeline fastener, 4 mounting plate, 5 telescopic rod, 6 socket, 7 vertical plate, 8 first threaded rod, 9 guide rod, 10 first motor, 11 sleeve plate, 12 moving plate, 13 fixed block, 14 second threaded rod, 15 lower sliding rod, 16 upper sliding rod, 17 moving sleeve block, 18 cross moving rod, 19 moving wheel, 20 second motor, 21 semi-circular frame, 22 semi-circular chute, 23 sliding block, 24 electric trolley, 25 welding torch, 26 end plate, 27 bidirectional threaded rod, 28 threaded sleeve block, 29 movable connecting rod, 30 contact block, 31 limiting groove, 32 limiting block, 33 rotating block. DETAILED DESCRIPTION OF THE INVENTION

[0017] The following embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0018] Reference Figures 1 - 6 , a metal pipe welding device for water conservancy construction, comprising a bottom plate 1, and the bottom plate 1 is laid on the construction tunnel through mud nails. Above the bottom plate 1, there are a first pipe fastener 2 and a second pipe fastener 3 distributed left and right. The first pipe fastener 2 and the second pipe fastener 3 are prior arts, and are assembled and fastened to the pipe through bolts. The first pipe fastener 2 is fixedly connected to the original metal pipe, and the second pipe fastener 3 is fixedly connected to the new metal pipe. It should be noted that the position height of the original metal pipe is in a fixed state and does not require support. A welding mechanism is arranged between the first pipe fastener 2 and the second pipe fastener 3. Both the lower ends of the first pipe fastener 2 and the second pipe fastener 3 are fixedly connected with mounting plates 4. Four telescopic rods 5 distributed in a rectangle are fixedly connected to the lower end of the mounting plate 4 on the left side. Four socket sleeves 6 distributed in a rectangle are fixedly connected to the upper end of the bottom plate 1. The telescopic ends of the four telescopic rods 5 are inserted into the corresponding socket sleeves 6. The four telescopic rods 5 and the first pipe fastener 2 play a role in connecting the original metal pipe and the bottom plate 1, and can prevent the position of the original metal pipe from changing in the horizontal direction.

[0019] On the upper end of the bottom plate 1 and below the mounting plate 4 on the right side, there is a moving mechanism. The moving mechanism includes two vertical plates 7 fixedly connected to the bottom plate 1 and distributed left and right. Between the two vertical plates 7, there are a first threaded rod 8 and a guide rod 9. The first threaded rod 8 is rotatably connected to the two vertical plates 7, and the guide rod 9 is fixedly connected to the two vertical plates 7. A first motor 10 for driving the first threaded rod 8 to rotate is fixedly installed on the vertical plate 7 on the right side. A sleeve plate 11 is sleeved on the first threaded rod 8 and the guide rod 9 together. The sleeve plate 11 is threadedly connected to the first threaded rod 8, and the sleeve plate 11 is slidably connected to the guide rod 9. The upper end of the sleeve plate 11 is fixedly connected to a moving plate 12. Four moving wheels 19 that are in rolling contact with the bottom plate 1 are installed at the lower end of the moving plate 12. The moving wheels 19 play a supporting role and do not affect the driving of the sleeve plate 11 and the moving plate 12 by the first motor 10.

[0020] At the upper end of the moving plate 12 and the lower end of the mounting plate 4 on the right side, four fixing blocks 13 distributed in a rectangle are fixedly connected. Between the two fixing blocks 13 on the moving plate 12 and on the right side, a second threaded rod 14 is rotatably connected therebetween. Between the two fixing blocks 13 on the moving plate 12 and on the left side, a downward sliding rod 15 is fixedly connected therebetween. Between every two front and rear corresponding fixing blocks 13 at the lower end of the mounting plate 4, an upward sliding rod 16 is fixedly connected therebetween. The lifting member includes two cross-activity rods 18 arranged coaxially. The rear ends of the two cross-activity rods 18 are respectively rotatably connected to the four fixing blocks 13 at the rear side. The front ends of the two cross-activity rods 18 are both rotatably connected with a moving sleeve block 17. The four moving sleeve blocks 17 are respectively sleeved on the second threaded rod 14, the downward sliding rod 15 and the upward sliding rod 16. The moving sleeve block 17 is threadedly connected to the second threaded rod 14 and is slidably connected to the downward sliding rod 15 and the upward sliding rod 16. Between every two left and right corresponding moving sleeve blocks 17, a connecting rod is fixedly connected therebetween. A second motor 20 for driving the second threaded rod 14 to rotate is fixedly installed on one of the fixing blocks 13. By driving the second threaded rod 14 to rotate, the second motor 20 can drive the upper moving sleeve block 17 to move back and forth. The four moving sleeve blocks 17 move synchronously, causing the two cross-activity rods 18 to cross-act, thereby driving the upper second pipe fastener 3 to lift, so as to conveniently move the new metal pipe to a position equal in height to the original metal pipe and keep it there.

[0021] The moving mechanism is connected to the mounting plate 4 on the right side through the lifting member. The lifting mechanism is used to adjust the position height of the new metal pipe so that it is consistent with the height of the original metal pipe, so as to use the moving mechanism to move its welding end to coincide with the welding end of the original metal pipe.

[0022] The welding mechanism includes a positioning ring sleeved on the new metal pipe. The positioning ring is composed of two semi-arc frames 21 arranged up and down opposite to each other. The two semi-arc frames 21 are connected by bolts. On the outer arc surfaces of the two semi-arc frames 21, semi-arc chutes 22 are respectively opened. The two semi-arc chutes 22 communicate with each other to form an annular chute. A sliding block 23 is slidably connected in the annular chute. When the two semi-arc frames 21 are assembled, the two semi-arc chutes 22 are communicated, and the sliding block 23 can slide in the annular chute formed by the two semi-arc chutes 22. One end of the sliding block 23 located outside the annular chute is fixedly installed with an electric trolley 24. The wheels of the electric trolley 24 rollingly contact the outer peripheral surface of the positioning ring. The electric trolley 24 is a prior art. It can be driven by electricity to make a circular motion around the positioning ring under the limiting action of the sliding block 23. A welding torch 25 is installed on the electric trolley 24. The welding torch 25 is a prior art. The welding torch 25 can move with the electric trolley 24, so as to make a circular motion around the positioning ring, and thus the welding work of the circumferential weld of the metal pipe can be carried out without rotating the metal pipe.

[0023] Two positioning and clamping mechanisms are provided on the inner arc surfaces of both semi-circular arc frames 21. The four positioning and clamping mechanisms are evenly distributed circumferentially. The positioning and clamping mechanism includes two end plates 26 fixedly connected to the inner wall of the semi-circular arc frame 21 and spaced left and right. A bidirectional threaded rod 27 is rotatably connected between the two end plates 26. Two symmetrically arranged threaded sleeve blocks 28 are threadedly sleeved on the bidirectional threaded rod 27. An active connecting rod 29 is rotatably connected to each of the two threaded sleeve blocks 28. The ends of the two active connecting rods 29 away from the threaded sleeve blocks 28 are rotatably connected together with a contact block 30. Transverse limiting grooves 31 are provided on the inner wall of the semi-circular arc frame 21 at positions corresponding to the respective threaded sleeve blocks 28. A limiting block 32 is slidably connected in each limiting groove 31. The end of the limiting block 32 away from the limiting groove 31 is fixedly connected to the corresponding threaded sleeve block 28. The limiting block 32 and the limiting groove 31 play a limiting role, so that the threaded sleeve block 28 can only move along the limiting groove 31. One end of the bidirectional threaded rod 27 penetrates through the end plate 26 and is coaxially fixedly connected with a rotating block 33. By rotating the rotating block 33, the relative movement of the two threaded sleeve blocks 28 can be controlled through the bidirectional threaded rod 27. When the two threaded sleeve blocks 28 move relatively, the contact block 30 can be driven to move through the active connecting rod 29.

[0024] The surface of the contact block 30 is provided with an arc-shaped rubber material. After the positioning ring is sleeved on the metal pipe, the four rotating blocks 33 can be rotated to make the four contact blocks 30 fit the surface of the metal pipe, so that the positioning ring is fixedly clamped on the metal pipe, thereby ensuring the stable welding work of the electric trolley 24 and the welding torch 25 above.

[0025] A welding method for a metal pipe welding device used in water conservancy construction is as follows: S1. First, dig a construction pit at the welding end of the original metal pipe. Lay the bottom plate 1 in the construction pit and fix it with mud nails. Then, fixedly sleeve the first pipe fastener 2 on the original metal pipe, and insert the four telescopic rods 5 below into the four socket sleeves 6 correspondingly. Then, fixedly sleeve the second pipe fastener 3 on the new metal pipe. S2. Assemble the two semi-circular arc frames 21 at a position near the welding end of the new metal pipe to form a positioning ring. By rotating each rotating block 33, the four contact blocks 30 are made to abut against the outer wall of the new metal pipe, so that the positioning ring is concentric with the new metal pipe. During the assembly process, the sliding block 23 is slidably installed in the semi-circular arc chute 22, and then the installation work of the electric trolley 24 and the welding torch 25 is completed. S3. Drive the lifting member to work through the second motor 20 to drive the new metal pipe to lift, so that the new metal pipe moves to a position at the same height as the original metal pipe. Then, drive the first threaded rod 8 to rotate through the first motor 10, and use the moving mechanism to drive the new metal pipe to move towards the original metal pipe until the welding ends of the two are in contact and coincide, so that the formed weld seam remains in a stable state. S4. Adjust the welding torch 25 so that its welding head is aligned with the weld seam, and then move it along the circular chute by the electric trolley 24, thereby driving the welding torch 25 to make a circular motion, that is, completing the welding work of the two metal pipes; S5. After welding is completed, disassemble and remove the first pipe fastener 2, the second pipe fastener 3, the positioning ring and the bottom plate 1, and then the welding work of the next section of metal pipe can be carried out.

[0026] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A metal pipe welding device for water conservancy construction, comprising a base plate (1), characterized in that: A first pipe fastener (2) and a second pipe fastener (3) are arranged on the top of the bottom plate (1) and are distributed on the left and right. A welding mechanism is arranged between the first pipe fastener (2) and the second pipe fastener (3). The lower ends of the first pipe fastener (2) and the second pipe fastener (3) are fixedly connected to a mounting plate (4). The lower end of the mounting plate (4) on the left is fixedly connected to four telescopic rods (5) distributed in a rectangular shape. A moving mechanism is arranged on the top of the bottom plate (1) and below the mounting plate (4) on the right. The moving mechanism is connected to the mounting plate (4) on the right through a lifting member. The first pipe fastener (2) is fastened to the original metal pipe, and the second pipe fastener (3) is fastened to the new metal pipe. The lifting mechanism is used to adjust the height of the new metal pipe so that it is consistent with the height of the original metal pipe, so that the welding end of the new metal pipe is moved to overlap with the welding end of the original metal pipe by using the moving mechanism.

2. A metal pipe welding device for water conservancy construction according to claim 1, characterized in that: Four rectangularly distributed insert sleeves (6) are fixedly connected to the upper end of the base plate (1), and the telescopic ends of the four telescopic rods (5) are inserted into corresponding insert sleeves (6).

3. A metal pipe welding device for water conservancy construction according to claim 1, characterized in that: The moving mechanism comprises two vertical plates (7) fixedly connected to the bottom plate (1) and distributed on the left and right sides, a first threaded rod (8) and a guide rod (9) are provided between the two vertical plates (7), the first threaded rod (8) is rotatably connected to the two vertical plates (7), the guide rod (9) is fixedly connected to the two vertical plates (7), a first motor (10) for driving the first threaded rod (8) to rotate is fixedly installed on the vertical plate (7) located on the right side, a sleeve plate (11) is sleeved on the first threaded rod (8) and the guide rod (9), the sleeve plate (11) is threadedly connected to the first threaded rod (8), the sleeve plate (11) is slidably connected to the guide rod (9), a moving plate (12) is fixedly connected to the upper end of the sleeve plate (11), and four moving wheels (19) that are in rolling contact with the bottom plate (1) are installed on the lower end of the moving plate (12).

4. A metal pipe welding device for water conservancy construction according to claim 3, characterized in that: The upper end of the movable plate (12) and the lower end of the mounting plate (4) located on the right are both fixedly connected with four rectangularly distributed fixed blocks (13); a second threaded rod (14) is rotatably connected between two of the fixed blocks (13) located on the right side of the movable plate (12); a lower sliding rod (15) is fixedly connected between two of the fixed blocks (13) located on the left side of the movable plate (12); an upper sliding rod (16) is fixedly connected between every two of the fixed blocks (13) located at the lower end of the mounting plate (4); and the lifting member comprises two coaxially arranged cross movable rods (18). The two cross movable rods The rear ends of the two cross movable rods (18) are rotatably connected to the four fixed blocks (13) on the rear side, and the front ends of the two cross movable rods (18) are rotatably connected to the movable sleeve blocks (17). The four movable sleeve blocks (17) are respectively sleeved on the second threaded rod (14), the lower slide rod (15) and the upper slide rod (16). The movable sleeve blocks (17) are threadedly connected to the second threaded rod (14) and slidably connected to the lower slide rod (15) and the upper slide rod (16). A connecting rod is fixedly connected between every two corresponding movable sleeve blocks (17) on the left and right, and a second motor (20) for driving the second threaded rod (14) to rotate is fixedly installed on one of the fixed blocks (13).

5. A metal pipe welding device for water conservancy construction according to claim 1, characterized in that: The welding mechanism comprises a positioning ring sleeved on the new metal pipe, the positioning ring is composed of two semi-arc frames (21) arranged opposite to each other in an upper and lower direction, the two semi-arc frames (21) are connected by bolts, the outer arc surfaces of the two semi-arc frames (21) are provided with semi-arc slide grooves (22), the two semi-arc slide grooves (22) are interconnected to form an annular slide groove, a sliding block (23) is slidably connected in the annular slide groove, an electric trolley (24) is fixedly installed at one end of the sliding block (23) located outside the annular slide groove, the wheel of the electric trolley (24) is in rolling contact with the outer peripheral surface of the positioning ring, a welding gun (25) is installed on the electric trolley (24), and two positioning clamping mechanisms are provided on the inner arc surfaces of the two semi-arc frames (21), and the four positioning clamping mechanisms are evenly distributed circumferentially.

6. A metal pipe welding device for water conservancy construction according to claim 5, characterized in that: The positioning and clamping mechanism comprises two end plates (26) fixedly connected to the inner wall of the semi-arc frame (21) and spaced apart from each other. A bidirectional threaded rod (27) is rotatably connected between the two end plates (26). Two threaded sleeves (28) symmetrically arranged on the two-way threaded rod (27) are threadedly sleeved. The two threaded sleeves (28) are rotatably connected to a movable connecting rod (29). One end of the two movable connecting rods (29) away from the threaded sleeves (28) is rotatably connected to a contact block (30). A limiting groove (31) is transversely provided on the inner wall of the semi-arc frame (21) and at a position corresponding to each threaded sleeve (28). A limiting block (32) is slidably connected in each limiting groove (31). One end of the limiting block (32) away from the limiting groove (31) is fixedly connected to the corresponding threaded sleeve (28). One end of the bidirectional threaded rod (27) passes through the end plate (26) and is coaxially fixedly connected to a rotating block (33).

7. A welding method for a metal pipe welding device for water conservancy construction according to claims 1-6, characterized in that: Here are the steps: S1. A construction tunnel is excavated at the welding end of the original metal pipe in advance, a base plate (1) is laid in the construction tunnel, and is fixed with mud nails, and then a first pipe fastener (2) is fixedly sleeved on the original metal pipe, and four telescopic rods (5) below are correspondingly inserted into four sockets (6), and then a second pipe fastener (3) is fixedly sleeved on the new metal pipe; S2, assembling the two semi-arc frames (21) at the position close to the welding end of the new metal pipe to form a positioning ring, and rotating the rotating blocks (33) so that the four contact blocks (30) are against the outer wall of the new metal pipe, so that the positioning ring and the new metal pipe are arranged concentrically, and during the assembly process, the sliding block (23) is slidably installed in the semi-arc sliding groove (22), and the installation of the electric trolley (24) and the welding gun (25) is completed; S3, driving the lifting member to work by the second motor (20) so as to drive the new metal pipe to move up and down, so that the new metal pipe moves to the same height as the original metal pipe, and then driving the first threaded rod (8) to rotate by the first motor (10), so as to drive the new metal pipe to move toward the original metal pipe by the moving mechanism until the welding ends of the two are in contact and overlap, so that the formed weld remains in a stable state; S4, adjusting the welding gun (25) so that the welding head is aligned with the weld, and then the electric trolley (24) is moved along the annular slideway, thereby driving the welding gun (25) to move in a circular motion, thus completing the welding of the two metal pipes; S5. After the welding is completed, the first pipe fastener (2), the second pipe fastener (3), the positioning ring and the base plate (1) are separated and removed, and the welding work of the next section of the metal pipe can be carried out.

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