Transformer flange welding method, flange positioning device and flange pipeline welding tool

Abstract

The present application belongs to the field of workpiece positioning, and specifically provides a transformer union pipe flange welding method, a flange positioning device and a flange pipe welding tool. The welding method comprises: ① respectively positioning and placing the union pipe and the flange on the union pipe positioning device and the flange positioning device, wherein the flange positioning device comprises a positioning seat, the positioning seat has a positioning groove, the flange is rotated in the positioning groove with the axis of the flange as a center axis by a proper angle, so that the bolt hole of the flange is in a correct position relative to the union pipe; ② welding the flange and the union pipe; ③ after the welding is completed, the movable disc and the flange are separated first, and then the whole composed of the flange and the union pipe is lifted to take out the flange from the positioning groove and the union pipe from the union pipe positioning device. The positioning device and the welding tool are used to realize the above welding method. After the welding is completed, the whole of the flange and the pipe can be lifted, at this time, the flange can be directly taken out from the positioning groove without moving other components, and the operation is convenient.

Description

Technical Field

[0001] This invention belongs to the field of workpiece positioning, and in particular relates to a method for welding transformer connecting flanges, a flange positioning device, and flange pipe welding fixtures. Background Technology

[0002] Transformer connecting pipes are important components of the cooling system, typically connected to radiators, oil tanks, etc., usually via flange connections. When assembling connecting pipes, the flange must first be welded to one end of the connecting pipe.

[0003] In complex large transformers, the connecting pipes are generally irregularly shaped, including bent sections. To ensure that the flange at one end of the connecting pipe can smoothly align with the flange to which it is connected, that is, to ensure that the bolts of the connecting flange can smoothly pass through the bolt holes of the flange, the bolt holes on the flange should have the correct angle relative to the connecting pipe.

[0004] Patent CN102489917B discloses a pipe assembly welding platform. This platform includes a workbench, a flange placement device (i.e., a flange positioning device), and a pipe placement device (i.e., a pipe positioning device). The flange placement device includes a fixed plate and a movable plate. The fixed plate is fixed to the workbench, and the movable plate is rotatably mounted on the fixed plate. The fixed plate has a scale indicating the rotation angle of the movable plate. The movable plate is equipped with support bolts for mounting the flange. These support bolts can be inserted into the bolt holes of the flange to support and position it. The pipe placement device supports the welding connection between the pipe and the flange.

[0005] Analysis of the structure of the welding platform for the above-mentioned pipeline assembly shows that, in the actual welding of flanges and pipelines, the rotating disc can be used to rotate the flange by a certain angle (the scale can be observed), so that the corresponding bolt holes of the flange are rotated to the appropriate position, thereby achieving the positioning of the flange, and on this basis, the welding of the flange and pipeline can be carried out.

[0006] Although the aforementioned piping group disclosed a design for a welding platform that allows for flange angle adjustment via flange rotation, some practical problems remain if this platform is directly applied to the welding positioning of transformer connecting pipes and flanges: For example, in the aforementioned platform, the flange placement device for the positioning flange only has a support bolt that mates with the flange, essentially meaning the flange is hung on the support bolt. To prevent axial movement of the flange, considering the description in the patent text that the moving plate is rotated and installed on the fixed plate, the axial connection between the moving plate and the fixed plate should be relatively reliable and difficult to disassemble. Thus, after the pipe and flange are welded, the flange can only be removed from the support bolt by axially moving the entire assembly formed by the welded flange and pipe. For straight pipes, the transformer and connecting pipe can be moved relative to the pipe placement device, or the pipe installation device can be moved to move the transformer and connecting pipe as a whole. However, the transformer's connecting pipe is not a straight pipe. To ensure pipe stability during welding, the pipe needs to be clamped at different positions with different clamping directions during positioning. Therefore, the flange can only be removed from the support bolt by moving the entire pipe placement device. This necessitates readjusting the pipe placement device for the next flange and pipe weld, making the operation inconvenient. Summary of the Invention

[0007] The purpose of this invention is to provide a method for welding transformer connecting flanges, thereby solving the technical problems in the prior art where flange and connecting pipe welding is inconvenient for positioning and welding, and where the need to adjust the pipe positioning device during removal leads to operational inconvenience. A further purpose of this invention is to provide a flange positioning device and flange-pipe welding fixture to solve the same technical problems.

[0008] To achieve the above objectives, the technical solution of the transformer connecting flange welding method provided by the present invention is as follows: A method for welding a transformer connecting pipe flange includes the following steps: ① Positioning the connecting pipe and flange on a connecting pipe positioning device and a flange positioning device, respectively. The flange positioning device includes a positioning seat with a positioning groove for the flange to be inserted from top to bottom and positioned radially and axially. A moving disc drives the flange to rotate at a suitable angle relative to the positioning seat in the positioning groove around its own axis, so that the bolt holes of the flange are in the correct position relative to the connecting pipe; ② Welding the flange and connecting pipe; ③ After the flange and connecting pipe are welded, the moving disc and the flange are separated first, and then the whole assembly of the flange and connecting pipe is lifted up so that the flange is removed from the positioning groove and the connecting pipe is removed from the connecting pipe positioning device.

[0009] As a further improvement, before step ②, the flange is locked in the positioned position using a locking device.

[0010] This invention is a pioneering creation, and its beneficial effects are as follows: When welding connecting pipes and flanges using the method of this invention, the position of the flange is determined by the positioning groove, and the position of the connecting pipe is determined by the connecting pipe positioning device. Specifically, the flange can be adjusted to rotate relative to the positioning seat in the positioning groove to ensure that the flange and connecting pipe are positioned and aligned, thereby enabling the welding of the flange and connecting pipe to be completed normally. In this invention, since the positioning groove is what positions the flange, the basic function of the moving plate is to drive the flange to rotate. It is sufficient to ensure that the moving plate can be separated from the flange after welding. After the moving plate is separated from the flange, the flange and connecting pipe as a whole formed after welding can be lifted to ensure that the flange can be removed from the positioning groove without adjusting the connecting pipe positioning device, making the operation more convenient.

[0011] To achieve the above objectives, the technical solution of the flange positioning device provided by the present invention is as follows: A flange positioning device includes a positioning seat and a movable plate. The positioning seat has an upward-facing positioning groove for inserting and removing the flange. The bottom surface of the positioning groove and the two side surfaces of the groove together form a positioning surface for determining the radial position of the flange. The positioning seat also has an axial positioning structure for engaging with both ends of the flange to determine the axial position of the flange. The movable plate has at least one protrusion for inserting a bolt hole into the flange to drive the flange to rotate. The positioning seat has a movable plate mounting hole for inserting and removing the movable plate and for rotating the movable plate. The movable plate has a pointer. The positioning seat has a positioning indicator structure for indicating that the movable plate has rotated to the correct position. A protrusion and the pointer are directly opposite each other in the axial direction of the movable plate or in the projection of the pointer in the axial direction. The protrusion and the pointer are directly opposite each other in the radial direction of the movable plate.

[0012] As a further improvement, the end of the flange used for welding to the pipe is defined as the front end, the positioning seat includes a seat body, and the axial positioning structure includes a front positioning structure for mating with the front end face of the flange, the front positioning structure including a limiting baffle fixed on the seat body.

[0013] As a further improvement, the base is provided with a mounting groove, and a limiting baffle is installed in the mounting groove and is flush with the front end of the base.

[0014] As a further improvement, the positioning seat is equipped with a locking screw with one end extending into the positioning groove to abut against the outer circumferential surface of the flange and lock the flange in the positioned position.

[0015] As a further improvement, the positioning indicator structure is a dial fixed on the positioning base.

[0016] As a further improvement, at least two locating pins are provided between the dial and the locating seat to position the dial and the seat.

[0017] This invention is a pioneering creation, and its beneficial effects are as follows: When using the flange positioning device of this invention, the welded flange can be placed in the positioning groove of the positioning seat. Under the limiting action of the positioning surface, the radial position of the flange can be determined. Simultaneously, the axial positioning structure can respectively cooperate with both ends of the flange to restrict its axial position. After the flange is placed in the positioning groove, the flange can be rotated within the groove by a moving disc. By observing the positioning indicator structure, the bolt holes of the flange can be adjusted to be in the correct position relative to the pipe. After welding is completed, the moving disc can be removed from the positioning seat and separated from the flange. At this point, lifting the flange and connecting pipe as a whole after welding ensures that the flange can be removed from the positioning groove without adjusting the connecting pipe positioning device, making operation more convenient.

[0018] To achieve the above objectives, the technical solution for the flange pipe welding fixture provided by this invention is as follows: A flanged pipe welding fixture includes a pipe positioning device and a flange positioning device. The pipe positioning device includes a straight section positioning structure for clamping a straight pipe section and a curved section positioning structure for clamping a curved pipe section and keeping the plane determined by the axes of the straight and curved pipe sections vertical. The flange positioning device includes a positioning seat and a movable plate. The positioning seat has a positioning groove with an upward opening for inserting and removing the flange. The bottom surface of the positioning groove and the two side surfaces of the groove together form a positioning surface for determining the radial position of the flange. The positioning seat also has an axial positioning structure for engaging with the axial ends of the flange to determine the axial position of the flange. The movable plate has at least one protrusion for inserting a bolt hole into the flange to drive the flange to rotate. The positioning seat has a movable plate mounting hole for inserting and removing the movable plate and for allowing the movable plate to rotate. The movable plate has a pointer. The positioning seat has a positioning indicator structure for indicating that the movable plate has rotated to the correct position. A protrusion and the pointer are directly opposite each other in the axial direction of the movable plate or in the axial projection. The protrusion and the pointer are directly opposite each other in the radial direction of the movable plate.

[0019] As a further improvement, the end of the flange used for welding to the pipe is defined as the front end, the positioning seat includes a seat body, and the axial positioning structure includes a front positioning structure for mating with the front end face of the flange, the front positioning structure including a limiting baffle fixed on the seat body.

[0020] As a further improvement, the base is provided with a mounting groove, and a limiting baffle is installed in the mounting groove and is flush with the front end of the base.

[0021] As a further improvement, the positioning seat is equipped with a locking screw with one end extending into the positioning groove to abut against the outer circumferential surface of the flange and lock the flange in the positioned position.

[0022] As a further improvement, the positioning indicator structure is a dial fixed on the positioning base.

[0023] As a further improvement, at least two locating pins are provided between the dial and the locating seat to position the dial and the seat.

[0024] As a further improvement, the bend positioning structure includes a base configured to move closer to and further away from the straight section positioning structure. The base is provided with an adjustment block that can be moved up and down to adjust its position. The adjustment block is provided with a clamping block that can be tilted and swung to adjust its position. The clamping block is provided with a slot for the pipe to enter.

[0025] This invention is a pioneering creation, and its beneficial effects are as follows: When using the flange pipe welding fixture of this invention, the pipe to be welded (not a straight pipe) can be held and positioned by the straight section positioning structure and the bend section positioning structure. The flange to be welded can be placed in the positioning groove of the positioning seat. Under the limiting action of the positioning surface, the radial position of the flange can be determined. At the same time, the axial positioning structure can respectively cooperate with both ends of the flange to restrict the axial position of the flange. After the flange is placed in the positioning groove, the flange can be rotated in the positioning groove by a moving plate. By observing the positioning indicator structure, the bolt holes of the flange can be adjusted to be in the correct position relative to the pipe. After welding is completed, the moving plate can be removed from the positioning seat and separated from the flange. At this time, the flange and the connecting pipe formed after welding can be lifted as a whole to ensure that the flange can be removed from the positioning groove without adjusting the connecting pipe positioning device, making the operation more convenient. Attached Figure Description

[0026] Figure 1 This is a perspective view of one of the embodiments of the flange pipe welding fixture in this invention; Figure 2 This is a perspective view of an embodiment of the flange pipe welding fixture in this invention from another angle; Figure 3 for Figure 1 Exploded view of the center flange positioning device; Figure 4 for Figure 1 Exploded view of the bend positioning structure in the pipeline positioning device.

[0027] Explanation of reference numerals in the attached figures: 1. Platform; 2. Positioning seat; 3. Flange; 4. Pipe; 5. Straight section positioning structure; 6. Bend section positioning structure; 201. Positioning groove; 202. Limiting baffle; 203. Moving disc; 204. Dial; 205. Locking screw; 206. Handle; 207. Mounting groove; 208. Positioning pin; 209. Connecting screw; 601. Base; 602. Guide rod; 603. Adjusting block; 604. Clamping block; 605. Rotating shaft; 606. Flat key. Detailed Implementation

[0028] The basic technical concept of this invention is to use an upward-facing positioning groove to determine the axial and radial positions of the flange. After the flange and the pipe are welded together, the flange and the pipe can be lifted as a whole. At this time, the flange can be directly removed from the positioning groove without moving other parts, which is convenient to operate.

[0029] Based on the above concept, the present invention will be further described in detail below with reference to embodiments.

[0030] Specific embodiments of the flange pipe welding fixture provided by this invention: The flange pipe welding fixture provided in this embodiment can be used for welding the connecting pipe and flange 3 of the transformer. Specifically, as shown in the example... Figures 1-4 As shown, the welding fixture includes a pipe positioning device and a flange positioning device, and naturally, also includes a platform 1 for placing and supporting these two devices. As the names suggest, the pipe positioning device is used to determine the position of the pipe 4, and the flange positioning device is used to determine the position of the flange 3. The flange positioning device is as follows... Figures 1-3 As shown, it includes a positioning seat 2, which is fixed in place during use, i.e., fixed relative to the platform 1. The fixing method can be welding, bolting, etc. The positioning seat 2 has a positioning groove 201, the opening of which faces upwards, allowing the flange 3 to be welded into place and also to be removed. The radial and axial positions of the flange 3 are determined by the positioning groove 201. Figure 1 As shown, the bottom surface of the positioning groove 201 and the side surfaces of the groove on both sides together form a positioning surface that determines the radial position of the flange 3. That is, the size of the positioning groove 201 is basically matched with the size of the flange 3 to be welded, and the height of the bottom surface of the positioning groove 201 is just enough to ensure that the axis of the flange 3 coincides with the axis of the positioned pipe 4 after the flange 3 is placed. Specifically, the bottom surface of the positioning groove 201 can be machined into an arc-shaped surface that matches the diameter of the flange 3. In this case, the bottom surface of the groove has a larger contact area with the flange 3. However, it should be noted that in other embodiments, the bottom surface of the groove may be flat. When applied to the welding of transformer connecting pipes and flange 3, since the model of flange 3 and the size of connecting pipe are both determined, the positioning seat 2 is specifically used for flange 3 of a certain size. It is easy to understand that the axial position of flange 3 also needs to be positioned. The positioning seat 2 is also provided with an axial positioning structure for cooperating with the two axial ends of flange 3 to determine the axial position of flange 3.

[0031] like Figure 1 , Figure 2 and Figure 4As shown, for irregularly shaped bends, the pipe positioning device consists of two parts: a straight section positioning structure 5 for clamping the straight section of pipe 4 and a bend section positioning structure 6 for clamping the curved section of pipe 4. The position of the bend section positioning structure 6 is such that, after it and the straight section positioning structure 5 clamp pipe 4 together, pipe 4 is in a vertically extending plane. In other words, the plane determined by the axis of the straight section and the axis of the curved section of the clamped pipe 4 should be a vertically extending plane. Specifically, both the straight section positioning structure 5 and the bend section positioning structure 6 are provided with clamping grooves (slots) capable of clamping pipe 4.

[0032] To ensure that flange 3 can be smoothly connected to flange 3 on another section of pipe 4 during use, i.e., to ensure that the bolt holes are aligned, in addition to ensuring that pipe 4 and flange 3 are coaxial, the bolt holes on flange 3 should have the correct angle relative to pipe 4. Therefore, before welding pipe 4 and flange 3, flange 3 is rotated to rotate the bolt holes to the correct position relative to pipe 4. To enable the rotation of flange 3, the flange positioning device also includes a movable plate 203, which can be inserted into and removed from the movable plate mounting hole provided on the positioning seat 2. The movable plate mounting hole is adapted to the diameter of the movable plate 203. The movable plate 203 is provided with a protrusion for adapting to the bolt hole inserted into flange 3, which can drive flange 3 to rotate. Due to the positioning groove 201, only one protrusion is required at most. The figure exemplifies a case where flange 3 has four bolt holes and four corresponding protrusions are provided on the movable plate 203.

[0033] To accurately determine whether flange 3 has rotated to the correct position, a pointer is provided on the moving plate 203, and a positioning seat 2 is provided with a position indicator structure to indicate whether the moving plate 203 has rotated to the correct position. To ensure that the pointer position directly reflects the position of the bolt holes on flange 3, regardless of the number of protrusions, one protrusion is axially aligned with the pointer on the moving plate 203, or, in the axial projection, the pointer and the protrusion are radially aligned on the moving plate 203. In practical use, the pointer's position directly indicates that the bolt holes on flange 3 are in position.

[0034] When welding connecting pipes and flanges 3 for transformers, the following method can be used: ① Place the connecting pipe and flange 3 on the connecting pipe positioning device (i.e., pipe positioning device) and flange positioning device respectively, in any order. Place the flange 3 into the positioning groove 201 of the positioning seat 2. At this time, the radial and axial positions of the flange 3 can be determined, and the position of the pipe 4 can also be determined. Then, use the moving plate 203 to drive the flange 3 to rotate at a suitable angle in the positioning groove 201 around its own axis, so that the bolt holes of the flange 3 are in the correct position relative to the connecting pipe. ② After the connecting pipe and flange 3 are positioned, weld the connecting pipe and flange 3. At this stage, welding can be done by electric welding. Ensure that flange 3 and connecting pipe do not separate, and then perform full welding later in a space that is easy to operate. Of course, full welding can also be done directly. ③ After the flange 3 and the connecting pipe are welded, separate the moving plate 203 from the flange 3 (specifically, the moving plate 203 can be directly removed from the positioning seat 2), lift the flange 3 and the connecting pipe as a whole so that the flange 3 can be taken out from the positioning groove 201 and the connecting pipe can be taken out from the connecting pipe positioning device.

[0035] Analysis of the above process shows that when the entire pipe 4 and flange 3 are removed after welding, the present invention does not require moving the pipe positioning device or the flange positioning device. Instead, the pipe 4 and flange 3 are directly lifted, making the operation more convenient. At the same time, both the flange positioning device and the pipe positioning device are in the appropriate position, which also facilitates normal welding next time.

[0036] For flange positioning devices, more specifically, such as Figure 1 and Figure 3 As shown, the positioning seat 2 includes an integral seat body, while the aforementioned axial positioning structure is partly assembled separately on the seat body of the positioning seat 2, and partly integrally formed with the seat body or constituted by a structure on the seat body. For ease of description, the end of the flange 3 used for welding with the pipe 4 can be defined as the front end. Naturally, the axial positioning structure also includes a front positioning structure and a rear positioning structure. The front positioning structure is used to mate with the front end face of the flange 3, specifically including a limiting baffle 202 fixedly installed on the seat body. The specific fixing method can be welding or bolt connection. In this case, the seat body is easier to process. That is to say, for the seat body itself, it only needs to ensure that it can mate with the rear end of the flange 3 to limit the position of the rear end of the flange 3. Of course, in other embodiments, it is not ruled out that a retaining step integral with the seat body may be separately processed on the seat body.

[0037] Furthermore, the figure exemplarily provides an implementation with two limiting baffles 202, which work together to achieve a better limiting effect. However, in other embodiments, the possibility of having only one limiting baffle 202 cannot be ruled out.

[0038] Furthermore, also refer to Figure 1 and Figure 3 The positioning seat 2 has a mounting groove 207 on its base, and a limiting baffle 202 is installed in the mounting groove 207 and flush with the front end of the base. The mounting groove 207 has a limiting function for the limiting baffle 202, which can ensure the stability of the limiting baffle 202. Moreover, the limiting baffle 202 is essentially embedded in the base, making the positioning seat 2 more integrated.

[0039] To prevent flange 3 from rotating under stress during the welding process between flange 3 and pipe 4 (connecting pipes), a locking device can be used to lock flange 3 in the pre-positioned position before welding.

[0040] Specifically, for flange positioning devices, such as Figure 2 and Figure 3 As shown, the positioning seat 2 is equipped with a locking screw 205, one end of which can extend into the positioning groove 201 to abut against the outer circumferential surface of the flange 3. After the locking screw 205 is tightened, the flange 3 is pressed against the position, which can prevent the flange 3 from loosening during the welding process and improve the welding accuracy.

[0041] In some cases, due to the internal structure of the transformer, the actual routing of the connecting pipes may differ. Even when using the same type of flange 3 and connecting pipe, the appropriate mating angle for flange 3 may vary. To make the flange positioning device applicable to flange 3 at other mating angles, such as... Figure 2 and Figure 3 As shown, the aforementioned positioning indicator structure is a dial 204 fixed on the positioning base 2. The dial 204 has a set range, such as 0° to 90°. In actual operation, the moving plate 203 can be rotated to the 0° position corresponding to the pointer, i.e., the vertical position. Then, according to the calculated angle information of the bolt holes and pipes 4, the moving plate 203 can be rotated. For example, if a flange 3 needs to be rotated 30°, rotating the moving plate 203 to the position corresponding to the 30° mark indicates that the flange 3 has been rotated into position.

[0042] However, it should be emphasized that in other embodiments, as a more specialized approach, the flange positioning device is only applicable to the same type of flange 3. The position of this flange 3 is actually relatively uniform. In this case, an indicator line can be set on the positioning seat 2 to serve as a positioning indicator structure.

[0043] To ensure the installation accuracy of dial 204, such as Figure 3 As shown, a positioning pin 208 is provided between the dial 204 and the positioning seat 2. At least two positioning pins 208 are provided (the figure shows exactly two positioning pins 208). The positioning pins 208 can be inserted into the positioning holes on the dial 204 and the positioning seat 2 to position the dial 204 and the positioning seat 2. After positioning, the positioning plate is fixed using connecting screws 209. During the tightening and fixing process, the dial 204 will not move, improving the installation accuracy of the dial 204.

[0044] For ease of operation, in some preferred embodiments, the moving plate 203 is also equipped with a handle 206.

[0045] Similarly, for cases where the connecting pipes have different routes, in the preferred embodiment, the bend positioning structure 6 in the pipe 4 positioning structure can also be configured as a flexibly adjustable structure. Specifically, such as Figure 1 , Figure 2 and Figure 4 As shown, the curved section positioning structure 6 includes a base 601, which is configured to move closer to and further away from the straight section positioning structure 5. Specifically, as an implementable method, a guide groove, such as a dovetail groove, can be provided on the platform 1, and a protrusion that can slide along the guide groove can be provided on the base 601. The base 601 is provided with an adjusting block 603 that can be moved up and down to adjust its position. Specifically, a guide rod 602 can be provided on the base 601, and the adjusting block 603 is fitted onto the guide rod 602 and can slide up and down along the guide rod 602. After adjustment, it can be locked with a tightening bolt. The adjusting block 603 is provided with a clamping block 604 that can tilt and swing, and the clamping block 604 is provided with a slot for the pipe 4 to enter. Specifically, the adjusting block 603 is provided with a rotating shaft 605 that can rotate relative to the adjusting block 603. The rotating shaft 605 and the clamping block 604 are connected to prevent rotation. Specifically, they can be connected by a flat key 606. Rotating the rotating shaft 605 can drive the clamping block 604 to pitch and swing. After it is in place, it is locked with a tightening bolt.

[0046] However, it should be noted that there are many other ways to move the base 601, the adjusting block 603, and the clamping block 604. For example, a guide rail ball slider mechanism can be set to make the base 601 relative to the platform 1, a screw nut mechanism can be set to make the adjusting block 603 move up and down, the existing rotating shaft 605 can be fixed on the adjusting block 603, and the clamping block 604 can be rotatably mounted on the rotating shaft 605. Those skilled in the art can flexibly set these up.

[0047] Similarly, for the pipe positioning structure 4 which is only applicable to the welding of the same type of flange 3 and connecting pipe, both the straight section positioning structure 5 and the bend section positioning structure 6 can be fixed in place.

[0048] Specific embodiments of the flange positioning device provided by the present invention: The embodiment of the flange positioning device is the flange positioning device described in the embodiment of the flange pipe welding fixture mentioned above, and will not be described in detail here.

[0049] Specific embodiments of the transformer connecting flange welding method provided by the present invention: The key to the transformer connecting flange welding method is to lift the flange and connecting pipe together after welding without moving the flange positioning device and the pipe positioning device (i.e., the connecting pipe positioning device), so as to remove them as a whole. The specific process is the same as the method described in the above-mentioned flange and pipe welding fixture examples, and will not be repeated here.

[0050] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still make modifications to the technical solutions described in the foregoing embodiments without creative effort, or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for welding transformer connecting flanges, characterized in that, Includes the following steps: ① Place the connecting pipe and flange on the connecting pipe positioning device and flange positioning device respectively. The flange positioning device includes a positioning seat with a positioning groove for the flange to be placed from top to bottom and positioned radially and axially. A moving disc drives the flange to rotate at a suitable angle relative to the positioning seat in the positioning groove around its own axis, so that the bolt holes of the flange are in the correct position relative to the connecting pipe; ② Weld the flange and connecting pipe; ③ After welding, first separate the moving disc and the flange, and then lift the flange and connecting pipe as a whole so that the flange can be removed from the positioning groove and the connecting pipe can be removed from the connecting pipe positioning device.

2. The transformer connecting flange welding method according to claim 1, characterized in that, Before step ②, use the locking device to lock the flange in the positioned position.

3. A flange positioning device, characterized in that, The device includes a positioning seat and a movable plate. The positioning seat has an upward-facing positioning groove for inserting and removing the flange. The bottom surface of the positioning groove and the side surfaces of the groove together form a positioning surface that determines the radial position of the flange. The positioning seat also has an axial positioning structure for engaging with the axial ends of the flange to determine the axial position of the flange. The movable plate has at least one protrusion for inserting a bolt hole into the flange to drive the flange to rotate. The positioning seat has a movable plate mounting hole for inserting and removing the movable plate and for rotating the movable plate. The movable plate has a pointer. The positioning seat has a positioning indicator structure for indicating that the movable plate has rotated to the correct position. A protrusion and the pointer are directly opposite each other in the axial direction of the movable plate or in the axial projection. The protrusion and the pointer are directly opposite each other in the radial direction of the movable plate.

4. The flange positioning device according to claim 3, characterized in that, The end of the flange used for welding to the pipe is defined as the front end. The positioning seat includes a seat body. The axial positioning structure includes a front positioning structure for mating with the front end face of the flange. The front positioning structure includes a limiting baffle fixed on the seat body.

5. The flange positioning device according to claim 4, characterized in that, The base is provided with an installation groove, and the limiting baffle is installed in the installation groove and is flush with the front end of the base.

6. The flange positioning device according to any one of claims 3-5, characterized in that, The positioning seat is equipped with a locking screw, one end of which can extend into the positioning groove to abut against the outer circumferential surface of the flange and lock the flange in the positioned position.

7. The flange positioning device according to any one of claims 3-5, characterized in that, The positioning indicator is a dial fixed on the positioning base.

8. The flange positioning device according to claim 7, characterized in that, At least two locating pins are provided between the dial and the locating seat to position the dial and the seat.

9. A flange pipe welding fixture, characterized in that, The device includes a pipe positioning device and a flange positioning device. The pipe positioning device includes a straight section positioning structure for clamping a straight pipe section and a curved section positioning structure for clamping a curved pipe section and keeping the plane defined by the axes of the straight pipe section and the curved section of the pipe vertical. The flange positioning device is the flange positioning device as described in any one of claims 3-8.

10. The flange pipe welding fixture according to claim 9, characterized in that, the bend... The segment positioning structure includes a base configured to move closer to and further away from the straight segment positioning structure. The base is provided with an adjustment block that can be moved up and down to adjust its position. The adjustment block is provided with a clamping block that can be tilted and swung to adjust its position. The clamping block is provided with a slot for the pipe to enter.

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