A positioning device for welding a short pipe flange

Abstract

The application discloses a positioning device for welding of a short pipe flange, which comprises a base, a switching piece arranged on the base, an expansion piece arranged on the switching piece, and an abutting piece arranged on the expansion piece. In the application, the expansion piece is driven by a screw rod and a plurality of groups of symmetrical linkage rods, so that four groups of push-pull blocks can be synchronously radially expanded and contracted, power output is uniform, the expansion range can be accurately adjusted, the positioning device can be flexibly adapted to short pipe flange workpieces with different inner diameters, the symmetrical expansion mode avoids positioning deviation caused by unilateral force, effectively guarantees the stability of centering and clamping, widens the application range of the positioning device, and improves the universality and adaptability of the positioning device.

Description

Technical Field

[0001] This invention relates to the field of flange welding equipment technology, specifically a positioning device for welding short pipe flanges. Background Technology

[0002] Positioning equipment for short pipe flange welding is a specialized device used in the welding process of short pipes and flanges to center, clamp, and position the short pipes and flanges. Its core function is to ensure that the short pipes and flanges are coaxially aligned, avoid misalignment during welding, assist in completing the welding process, improve welding accuracy and efficiency, adapt to the batch welding needs of short pipe flanges of different specifications, and achieve coordinated operation of centering clamping and workpiece rotation, simplifying the welding operation process and reducing errors caused by manual positioning.

[0003] Existing positioning equipment for short pipe flange welding still has room for improvement in terms of the synchronicity and adaptability of clamping adjustment. The extension and retraction of its clamping components are difficult to achieve synchronous linkage, the power transmission is not uniform enough, the adjustment accuracy of the clamping amplitude is insufficient, and it cannot flexibly adapt to short pipe flange workpieces with various inner diameter specifications. Moreover, uneven force is prone to occur during the clamping process, affecting the stability of centering clamping. As a result, the equipment has a narrow range of applications, and its versatility and adaptability fail to fully meet the diverse needs of actual batch welding. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing positioning devices for short pipe flange welding. These devices have limitations in terms of the synchronicity and adaptability of clamping adjustment, the difficulty in achieving synchronous linkage of the extension and retraction of clamping components, uneven power transmission, insufficient adjustment precision of clamping amplitude, inability to flexibly adapt to short pipe flange workpieces with various inner diameters, and the tendency for uneven force during clamping, which affects the stability of centering clamping. Consequently, the devices have a narrow range of applications and their versatility and adaptability fail to fully meet the diverse needs of actual batch welding. Therefore, this invention provides a positioning device for short pipe flange welding.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a positioning device for welding short pipe flanges, comprising: a base, wherein the base is provided with a switching component, the switching component is provided with an expansion component, and the expansion component is provided with an abutment component; The switching component includes a placement plate disposed at the top of the base. A first insertion groove is formed through the center of the top of the placement plate. A connecting groove is formed at the center of the top of the placement plate. A motor is fixedly connected to the center of the bottom of the base. A pin is fixedly connected to the output end of the motor. A rotating seat is rotatably connected in the connecting groove. A second insertion groove is formed at the bottom of the rotating seat. The pin is slidably inserted into the first insertion groove or the second insertion groove. The expansion member includes a rotating shaft fixedly connected to the top of the rotating seat. A screw is fixedly connected to the top of the rotating shaft. A connecting sleeve is rotatably disposed on the outside of the rotating shaft, and the rotating shaft passes through the upper and lower ends of the connecting sleeve. A connecting rod is fixedly connected to the outside of the connecting sleeve. A connecting sleeve is engaged with the outside of the screw, and the screw passes through the connecting sleeve. A connecting rod is fixedly connected to the outside of the connecting sleeve. An adjusting rod is rotatably connected to one end of the connecting rod. A push-pull block is rotatably connected to one end of the adjusting rod. An adjusting rod is rotatably connected to one end of the push-pull block. One end of the adjusting rod is rotatably connected to the connecting rod.

[0006] As a further embodiment of the present invention: the bottom end of the placement plate abuts against the top end of the base, and a hydraulic rod is fixedly connected to the bottom end of the base. The hydraulic rod is provided in four sets and is distributed in an array at the bottom end of the base.

[0007] As a further embodiment of the present invention: the movable end of the hydraulic rod passes through the base and is fixedly connected to a rotating ring; four sets of hydraulic rods are fixedly connected to a rotating ring; the rotating ring is embedded in the bottom of the placement plate and is rotatably connected to the placement plate.

[0008] As a further embodiment of the present invention: the first insertion slot is cross-shaped, the top of the insertion post is cross-shaped, the second insertion slot is cross-shaped, and the cross-shaped insertion area at the top of the insertion post has the same depth as the second insertion slot.

[0009] As a further embodiment of the present invention: the rotating shaft is I-shaped, the first connecting rod is provided in four sets, symmetrically distributed on the outside of the first connecting sleeve, and the second connecting rod is provided in four sets, symmetrically distributed on the outside of the second connecting sleeve.

[0010] As a further embodiment of the present invention: the first adjusting rod and the second adjusting rod are symmetrically distributed on both sides of the push-pull block, and the first adjusting rod, the push-pull block and the second adjusting rod are arranged in a V-shape. There are four sets of the first adjusting rod, the push-pull block and the second adjusting rod, symmetrically distributed on the outside of the screw.

[0011] As a further embodiment of the present invention: the abutting member includes a movable groove formed at the top of the placement tray, a movable block slidably connected in the movable groove, the top of the movable block passing through the movable groove and fixedly connected to an abutting rod, the abutting rod having a lifting groove on the side facing the screw, a lifting block slidably connected in the lifting groove, one side of the lifting block passing through the lifting groove and fixedly connected to a push-pull block.

[0012] As a further embodiment of the present invention: the moving groove is convex, the moving block is convex, the bottom end of the abutting rod is in contact with the top end of the placement plate, the side of the abutting rod away from the screw is an arc surface, the lifting block is convex, and four sets of abutting members are provided, symmetrically distributed on the outside of the screw.

[0013] Compared with the prior art, the beneficial effects of the present invention are: 1. In this invention, the switching component can quickly switch the power output of the motor by means of the plug-in cooperation between the hydraulic rod and the cross-shaped plug, realizing the centering clamping drive and the workpiece rotation drive respectively. There is no need to add an additional independent drive component, which effectively simplifies the overall structure of the equipment and reduces manufacturing costs. This structure accurately matches the core processes of clamping, positioning and rotating welding of short pipe flange welding, reduces the equipment disassembly and debugging steps between processes, and greatly improves the process connection efficiency of welding operations. 2. In this invention, the expansion component relies on the transmission cooperation between the screw and multiple sets of symmetrical linkage rods to achieve synchronous radial extension and retraction of four sets of push-pull blocks. The power output is uniform and consistent, and the expansion amplitude can be precisely adjusted. It can flexibly adapt to short pipe flange workpieces with different inner diameter specifications. The symmetrical expansion method avoids positioning deviation caused by unilateral force, effectively ensures the stability of centering and clamping, broadens the application range of the equipment, and improves the versatility and adaptability of the device. 3. In this invention, the convex-shaped limiting sliding structure in the abutment component can precisely constrain the movement trajectory of the abutment rod, avoiding problems such as running jamming and deviation. The abutment rod adopts an arc surface design, which effectively increases the contact area with the inner wall of the short pipe, firmly clamps the workpiece, avoids radial shaking of the workpiece during welding, strictly ensures the coaxiality of the welding between the short pipe and the flange, and improves the overall welding forming quality and operation accuracy. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the switching component in this invention; Figure 3 In this invention Figure 2 A cross-sectional view of the structure at point A; Figure 4 In this invention Figure 2 A schematic diagram of the structure at location B of the placement plate; Figure 5 In this invention Figure 2 The structural cross-sectional view at point B; Figure 6 This is a schematic diagram of the expansion member in this invention; Figure 7 In this invention Figure 6 A schematic diagram of the structure at point C; Figure 8 This is a schematic diagram of the structure of the abutment member in this invention; Figure 9 In this invention Figure 8 A schematic diagram of the structure at point D; Figure 10 In this invention Figure 8 A schematic diagram of the structure at point E.

[0015] In the diagram: 1. Base; 2. Switching component; 21. Hydraulic rod; 22. Rotating ring; 23. Placement plate; 24. Insertion slot one; 25. Connecting slot; 26. Motor; 27. Insertion post; 28. Rotating seat; 29. ​​Insertion slot two; 3. Expansion component; 31. Rotating shaft; 32. Screw; 33. Connecting sleeve one; 34. Connecting rod one; 35. Connecting sleeve two; 36. Connecting rod two; 37. Adjusting rod one; 38. Push-pull block; 39. Adjusting rod two; 4. Abutment component; 41. Lifting block; 42. Moving slot; 43. Moving block; 44. Abutment rod; 45. Lifting slot. Detailed Implementation

[0016] 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.

[0017] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. In the description of this invention, it should be noted that unless otherwise explicitly specified and limited, the terms "installed," "connected," "linked," and "set up" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. The following describes embodiments of the invention based on its overall structure.

[0018] Reference Figure 1 In this embodiment of the invention, a positioning device for welding short pipe flanges includes: a base 1, a switching component 2, an expansion component 3 on the switching component 2, and an abutment component 4 on the expansion component 3.

[0019] Reference Figures 2 to 5The switching component 2 includes four sets of hydraulic rods 21 fixedly connected to the bottom end of the base 1. The hydraulic rods 21 are arranged in an array at the bottom end of the base 1. The movable end of each hydraulic rod 21 passes through the base 1 and is fixedly connected to a rotating ring 22. All four sets of hydraulic rods 21 are fixedly connected to one rotating ring 22. A placement plate 23 is provided at the top of the base 1. The rotating ring 22 is embedded in the bottom end of the placement plate 23 and rotatably connected to it. A cross-shaped insertion slot 24 is formed at the center of the top of the placement plate 23. A connecting slot 25 is formed at the center of the top of the placement plate 23. A motor 26 is fixedly connected to the center of the bottom end of the base 1. A pin 27 with a cross-shaped top is fixedly connected to the output end of the motor 26 and passes through the base 1. A rotating seat 28 is rotatably connected within the connecting groove 25. The bottom of the rotating seat 28 has a second insertion groove 29, which is cross-shaped. The insertion post 27 slides into either the first insertion groove 24 or the second insertion groove 29, with the cross-shaped insertion area at the top of the insertion post 27 matching the depth of the second insertion groove 29. Initially, the hydraulic rod 21 is in a retracted state, with the top of the base 1 abutting against the bottom of the placement plate 23. The insertion post 27 penetrates the base 1 and the first insertion groove 24, and its cross-shaped insertion area engages with the second insertion groove 29, allowing the insertion post 27 to drive the rotating seat 28 to rotate. When the hydraulic rod 21 extends, it lifts the rotating ring 22 and the placement plate 23, causing the cross-shaped insertion area at the top of the insertion post 27 to exit the second insertion groove 29 and slide into the first insertion groove 24. At this time, the insertion post 27 can drive the placement plate 23 to rotate.

[0020] The above solution, through the coordinated arrangement of hydraulic rod 21, rotating ring 22, placement plate 23, motor 26, insertion column 27, and rotating seat 28, enables precise switching of the power output object of the equipment. It can drive the rotating seat 28 or the placement plate 23 to operate independently, adapting to the power requirements of different processes such as centering clamping and rotary welding in short pipe flange welding, and expanding the functional adaptability range of the equipment.

[0021] Reference Figures 6 to 7The expansion member 3 includes a rotating shaft 31 fixedly connected to the top of the rotating seat 28. The rotating shaft 31 is I-shaped. A screw 32 is fixedly connected to the top of the rotating shaft 31. A connecting sleeve 33 is rotatably disposed on the outside of the rotating shaft 31, and the rotating shaft 31 passes through the upper and lower ends of the connecting sleeve 33. A connecting rod 34 is fixedly connected to the outside of the connecting sleeve 33. Four sets of connecting rods 34 are symmetrically distributed on the outside of the connecting sleeve 33. A connecting sleeve 35 is engaged with the outside of the screw 32, and the screw 32 passes through the connecting sleeve 35. A connecting rod 36 is fixedly connected to the outside of the connecting sleeve 35. Four sets of adjustment rods are provided on the outside of the connecting sleeve 35. One end of the connecting rod 34 is rotatably connected to the adjusting rod 37. One end of the adjusting rod 37 is rotatably connected to the push-pull block 38. One end of the push-pull block 38 is rotatably connected to the adjusting rod 39. One end of the adjusting rod 39 is rotatably connected to the connecting rod 36. The adjusting rods 37 and 39 are mirror images symmetrically distributed on both sides of the push-pull block 38. The adjusting rods 37, 38, and 39 are arranged in a V-shape. Four sets of the adjusting rods 37, 38, and 39 are symmetrically distributed on the outside of the screw 32.

[0022] The above scheme achieves synchronous radial displacement of four sets of push-pull blocks 38 through the linkage structure of rotating shaft 31, screw 32, connecting sleeve 1 33, connecting rod 1 34, connecting sleeve 2 35, connecting rod 2 36, adjusting rod 1 37, push-pull block 38, and adjusting rod 2 39. The power transmission is uniform and stable, providing a smooth and controllable expansion power for the centering and clamping of short pipe flanges, and adapting to the clamping and adjustment requirements of short pipes of different diameters.

[0023] Reference Figures 8 to 10 The abutment 4 includes a movable groove 42 formed at the top of the placement tray 23. The movable groove 42 is U-shaped. A movable block 43 is slidably connected in the movable groove 42. The movable block 43 is U-shaped. The top of the movable block 43 passes through the movable groove 42 and is fixedly connected to an abutment rod 44. The bottom end of the abutment rod 44 is in contact with the top of the placement tray 23. The side of the abutment rod 44 away from the screw 32 is arc-shaped. A lifting groove 45 is formed on the side of the abutment rod 44 facing the screw 32. A lifting block 41 is slidably connected in the lifting groove 45. One side of the lifting block 41 passes through the lifting groove 45 and is fixedly connected to the push-pull block 38. The lifting block 41 is U-shaped. Four sets of abutment 4 are provided, symmetrically distributed on the outside of the screw 32.

[0024] The above solution is adopted: through the limiting sliding cooperation of the moving groove 42, the moving block 43, the abutment rod 44, the lifting groove 45, and the lifting block 41, the stability of the movement of the abutment rod 44 is ensured. The arc surface structure can increase the contact area with the inner wall of the short pipe, realize the precise centering and clamping of the short pipe flange, avoid workpiece displacement during welding, and improve the coaxial accuracy of welding.

[0025] The working principle of this invention is as follows: In the initial state, the hydraulic rod 21 is in a retracted state, and the top of the base 1 is tightly fitted with the bottom of the placement plate 23, achieving stable support and limiting of the placement plate 23. The cross structure at the top of the insertion post 27 is precisely inserted into the insertion slot 29. At this time, the motor 26 outputs power to drive the rotating seat 28 to rotate alone, providing a dedicated power source for centering and clamping the workpiece. During operation, the operator first places the short pipe to be welded and the matching flange in sequence on the top plane of the placement plate 23, and then coaxially sleeves the short pipe and flange on the outside of the four sets of abutment rods 44, so that the bottom surface of the flange is tightly fitted with the flat surface of the placement plate 23, completing the initial positioning and orderly placement of the workpiece, avoiding the problem of initial workpiece skew. Then, the motor 26 is started. The output of motor 26 drives the insertion post 27 to rotate smoothly and at a uniform speed. The insertion post 27, through the interlocking transmission of the cross structure and the second insertion slot 29, drives the rotating seat 28 to rotate synchronously. The rotating seat 28 further drives the rotating shaft 31 at the top to rotate coaxially with the screw 32. When the screw 32 rotates, through the threaded engagement, it drives the second connecting sleeve 35 to move smoothly along the axial direction of the screw 32. The second connecting sleeve 35 synchronously drives the second connecting rod 36 to swing. With the fixed position of the first connecting rod 34, the V-shaped linkage structure formed by the first adjusting rod 37 and the second adjusting rod 39 drives the push-pull block 38 to expand radially outward synchronously. When the push-pull block 38 moves, it drives the lifting block 41 to slide smoothly along the lifting groove 45, thereby pushing the abutment rod 44 through the moving block 43 along the moving groove 45. 2. The four sets of abutment rods 44 move outward at a uniform speed, and their arc-shaped structures synchronously and evenly fit against the inner walls of the short pipe and flange, accurately completing the centering and clamping operation of the short pipe and flange. This ensures that the short pipe and flange are coaxially aligned, eliminating positional deviations before welding. After centering, the four sets of hydraulic rods 21 are controlled to extend synchronously and evenly. The hydraulic rods 21 lift the rotating ring 22 and the placement plate 23 upward, allowing the cross structure at the top of the insertion post 27 to smoothly exit the insertion slot 29 and slide into the insertion slot 24, completing the rapid switching of the power drive object. At this time, the power of the motor 26 is switched to drive the placement plate 23 to rotate as a whole, causing the short pipe and flange after centering and clamping to rotate at a uniform speed in a circular motion. This ensures that the joint gap between the short pipe and flange rotates at a uniform speed during welding, completing the full circumferential rotation. During the weekly welding operation, the expansion piece 3 maintains a stable clamping force throughout the welding process, effectively preventing the workpiece from loosening, shifting, or shaking during the rotational welding process. After welding is completed, the control motor 26 rotates in the reverse direction at a low speed, and the screw 32 rotates in the reverse direction, driving the connecting sleeve 35 to move. The push-pull block 38 retracts inward synchronously, and the abutment rod 44 releases the clamping limit on the short pipe. Then, the control hydraulic rod 21 retracts and resets, and the insertion post 27 re-inserts precisely into the insertion slot 29. The equipment returns to its initial working state, and the operator can remove the processed short pipe flange workpiece and quickly start the welding operation of the next set of workpieces. The overall process is smooth and seamless, with precise and controllable positioning, effectively adapting to the operational needs of batch welding processing of short pipe flanges.The switching component 2 allows for rapid switching of the power output of the motor 26 via the insertion and engagement of the hydraulic rod 21 and the cross-shaped insert 27, enabling both centering clamping drive and workpiece rotation drive. This eliminates the need for additional independent drive components, effectively simplifying the overall equipment structure and reducing manufacturing costs. This structure precisely matches the core processes of clamping, positioning, and rotating welding in short pipe flange welding, reducing equipment disassembly and debugging steps between processes and significantly improving the efficiency of welding process connections. The expansion component 3, relying on the transmission and engagement of the screw 32 and multiple sets of symmetrically linked rods, enables the synchronous radial extension and retraction of four sets of push-pull blocks 38, resulting in uniform and consistent power output. The adjustable expansion range allows for flexible adaptation to short pipe flanges with different inner diameters. The symmetrical expansion method avoids positioning deviations caused by unilateral force, effectively ensuring the stability of centering and clamping, broadening the equipment's applicability, and improving its versatility and adaptability. The convex-shaped limiting sliding structure in the abutment component 4 precisely constrains the movement trajectory of the abutment rod 44, preventing problems such as jamming and offset. The abutment rod 44 features an arc surface design, effectively increasing the contact area with the inner wall of the short pipe, firmly clamping the workpiece, preventing radial swaying during welding, strictly ensuring the coaxiality of the short pipe and flange welding, and improving the overall welding quality and operational accuracy.

[0026] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A positioning device for welding short pipe flanges, comprising: The base (1) is characterized in that the base (1) is provided with a switching component (2), the switching component (2) is provided with an expansion component (3), and the expansion component (3) is provided with an abutment component (4). The switching component (2) includes a placement plate (23) disposed at the top of the base (1). A first insertion slot (24) is provided through the center of the top of the placement plate (23). A connecting slot (25) is provided at the center of the top of the placement plate (23). A motor (26) is fixedly connected to the center of the bottom end of the base (1). A plug (27) is fixedly connected to the output end of the motor (26). A rotating seat (28) is rotatably connected in the connecting slot (25). A second insertion slot (29) is provided at the bottom end of the rotating seat (28). The plug (27) is slidably inserted into the first insertion slot (24) or the second insertion slot (29). The expansion member (3) includes a rotating shaft (31) fixedly connected to the top of the rotating seat (28). A screw (32) is fixedly connected to the top of the rotating shaft (31). A connecting sleeve (33) is rotatably provided on the outside of the rotating shaft (31), and the rotating shaft (31) passes through the upper and lower ends of the connecting sleeve (33). A connecting rod (34) is fixedly connected to the outside of the connecting sleeve (33). A connecting sleeve (35) is meshed with the outside of the screw (32), and the screw (32) passes through the connecting sleeve (35). A connecting rod (36) is fixedly connected to the outside of the connecting sleeve (35). An adjusting rod (37) is rotatably connected to one end of the connecting rod (34). A push-pull block (38) is rotatably connected to one end of the adjusting rod (37). An adjusting rod (39) is rotatably connected to one end of the push-pull block (38). One end of the adjusting rod (39) is rotatably connected to the connecting rod (36).

2. The positioning device for welding short pipe flanges according to claim 1, characterized in that, The bottom end of the placement plate (23) abuts against the top end of the base (1). The bottom end of the base (1) is fixedly connected to a hydraulic rod (21). The hydraulic rod (21) is arranged in four groups and distributed in an array at the bottom end of the base (1).

3. The positioning device for welding short pipe flanges according to claim 2, characterized in that, The movable end of the hydraulic rod (21) passes through the base (1) and is fixedly connected to a rotating ring (22). The four sets of hydraulic rods (21) are fixedly connected to a set of rotating rings (22). The rotating ring (22) is embedded in the bottom of the placement plate (23) and is rotatably connected to the placement plate (23).

4. The positioning device for welding short pipe flanges according to claim 3, characterized in that, The first insertion slot (24) is cross-shaped, the top of the insertion post (27) is cross-shaped, the second insertion slot (29) is cross-shaped, and the cross-shaped insertion area at the top of the insertion post (27) is the same depth as the second insertion slot (29).

5. A positioning device for welding short pipe flanges according to claim 4, characterized in that, The rotating shaft (31) is I-shaped. There are four sets of connecting rod one (34) symmetrically distributed on the outside of connecting sleeve one (33). There are four sets of connecting rod two (36) symmetrically distributed on the outside of connecting sleeve two (35).

6. A positioning device for welding short pipe flanges according to claim 5, characterized in that, The first adjusting rod (37) and the second adjusting rod (39) are symmetrically distributed on both sides of the push-pull block (38). The first adjusting rod (37), the push-pull block (38) and the second adjusting rod (39) are arranged in a V-shape. There are four sets of the first adjusting rod (37), the push-pull block (38) and the second adjusting rod (39), which are symmetrically distributed on the outside of the screw (32).

7. A positioning device for welding short pipe flanges according to claim 6, characterized in that, The abutting member (4) includes a movable groove (42) opened at the top of the placement tray (23). A movable block (43) is slidably connected in the movable groove (42). The top of the movable block (43) passes through the movable groove (42) and is fixedly connected to an abutting rod (44). A lifting groove (45) is opened on the side of the abutting rod (44) facing the screw (32). A lifting block (41) is slidably connected in the lifting groove (45). One side of the lifting block (41) passes through the lifting groove (45) and is fixedly connected to the push-pull block (38).

8. A positioning device for welding short pipe flanges according to claim 7, characterized in that, The moving groove (42) is convex, the moving block (43) is convex, the bottom end of the abutting rod (44) is attached to the top of the placement plate (23), the side of the abutting rod (44) away from the screw (32) is arc-shaped, the lifting block (41) is convex, and the abutting member (4) is provided in four sets, symmetrically distributed on the outside of the screw (32).

Images