Marine low-speed machine EGR stainless steel gas pipeline welding tool and using method

Abstract

The invention provides a marine low-speed machine EGR stainless steel gas pipeline welding tool and a using method. The marine low-speed machine EGR stainless steel gas pipeline welding tool comprises a tool workbench, a guide rail, a first elbow positioning frame, a second elbow positioning frame, a straight pipe positioning frame and a base pressing limiting device. The guide rail is fixedly arranged on the tool workbench, and the elbow positioning frame and the straight pipe positioning frame are both arranged on the guide rail. The first elbow positioning frame is arranged at one end of the straight pipe positioning frame, the second elbow positioning frame is arranged at the other end of the straight pipe positioning frame, the first elbow positioning frame and the second elbow positioning frame are both composed of supporting plates with different heights, and the straight pipe positioning frame is composed of supporting plates with the same height. An arc-shaped opening is formed in the upper end of the supporting plate, and the lower end of the supporting plate is fixed to the tool workbench through a fixing plate. By means of the multiple limiting structures, welding defects caused by instability of the tool are reduced, errors of pipeline installation are effectively reduced, and the problem that the welding qualification rate of pipeline manufacturing is low is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of welding clamping tooling, and particularly relates to a welding tooling for the EGR stainless steel gas pipeline of marine low-speed engines and a using method thereof. Background Technique

[0002] The statements in this part only provide background technical information related to the present invention and do not necessarily constitute prior art.

[0003] In the EGR (Exhaust Gas Recirculation) system of marine low-speed engines, the stainless steel gas pipeline is a key component, and its welding quality plays a decisive role in the performance and reliability of the entire system. With the increasingly wide application of the EGR system, higher standards have been put forward for the installation accuracy and welding quality of the gas pipeline.

[0004] Traditional gas pipeline welding methods are difficult to ensure the precise position of the pipeline before welding, easily generate large installation errors, resulting in poor weld accuracy and consistency, insufficient versatility and flexibility of the tooling, and being unable to meet the welding requirements of gas pipelines with different sizes, shapes and layouts. When facing pipelines with complex structures and different types of flange connections, it is often difficult to meet the precise positioning requirements, resulting in low welding efficiency and unstable welding quality. During the welding process, due to the lack of effective fixing and limiting measures, the pipeline is prone to move or rotate, which will cause discontinuous welding inside the weld, large welding size deviations, increase the rework cost and time cost, and it is difficult to meet the requirements of the shipbuilding industry for high-efficiency and high-quality production. Summary of the Invention

[0005] Aiming at the above problems, the present invention provides a welding tooling for the EGR stainless steel gas pipeline of marine low-speed engines and a using method thereof. By means of a multi-limiting structure, welding defects caused by the instability of the tooling are reduced, the installation error of the pipeline is effectively reduced, the problem of low welding qualification rate of the pipeline manufacturing with spatial dimensions is solved, the accuracy and consistency of the weld are improved, and the welding efficiency and quality are enhanced.

[0006] To achieve the above object, the present invention is realized by the following technical solutions:

[0007] In a first aspect, the present invention provides a welding tooling for the EGR stainless steel gas pipeline of marine low-speed engines, including: a tooling workbench, a guide rail, an elbow positioning frame, a straight pipe positioning frame and a base pressing limit; the guide rail is fixedly arranged on the tooling workbench, and both the elbow positioning frame and the straight pipe positioning frame are arranged on the guide rail;

[0008] The elbow positioning frame includes a first elbow positioning frame and a second elbow positioning frame; the first elbow positioning frame is arranged at one end of the straight pipe positioning frame, the second elbow positioning frame is arranged at the other end of the straight pipe positioning frame, both the first elbow positioning frame and the second elbow positioning frame are composed of support plates with different heights, the straight pipe positioning frame is composed of support plates with the same height, an arc-shaped opening is arranged at the upper end of the support plate, and a fixing plate is arranged at the lower end. The fixing plate is pressed, limited and fixed on the tooling workbench through the base.

[0009] As a further implementation method, it further includes: upper and lower pressing and limiting, which is arranged on one side of the tooling workbench; the upper and lower pressing and limiting is composed of a vertical support rod, a horizontal support rod and a pressing rod. The lower end of the vertical support rod is fixedly arranged on the tooling workbench, one end of the horizontal support rod is fixedly arranged at the top of the vertical support rod, and the other end of the horizontal support rod is threadedly connected with the pressing rod, so that the pressing rod can move vertically to realize the pressing of the pipeline.

[0010] As a further implementation method, the guide rail includes a first guide rail, a second guide rail and a third guide rail; the second guide rail is arranged at one end of the first guide rail, and the third guide rail is arranged at the other end of the first guide rail; the straight pipe positioning frame is slidably arranged on the first guide rail, the first elbow positioning frame is slidably arranged on the second guide rail, and the second elbow positioning frame is slidably arranged on the first guide rail.

[0011] As a further implementation method, a first flange positioning device is slidably arranged on the second guide rail, and a second flange positioning device is slidably arranged on the third guide rail.

[0012] As a further implementation method, the first flange positioning device is composed of a first ring, a first fixing frame and a mounting plate. The lower end of the mounting plate is slidably arranged on the fixing plate and is positioned by pressing and limiting through the base. The upper end of the mounting plate is fixedly connected with the first fixing frame. The first ring is arranged on the first fixing frame, and there is an included angle with a set angle between the first fixing frame and the mounting plate;

[0013] The second flange positioning device is composed of a second ring and a second fixing frame. The lower end of the second fixing frame is installed on the fixing plate, and the second ring is installed at the upper end.

[0014] As a further implementation method, the multiple support plates of the first elbow positioning frame are parallel to each other, and an auxiliary plate is arranged perpendicular to the multiple support plates. The multiple support plates are all perpendicular to the auxiliary plate to form a cross-shaped structure, which is used to improve the stability of the positioning frame at the elbow of the gas pipeline.

[0015] As a further implementation method, the second elbow positioning bracket further includes two auxiliary plates perpendicular to each other, and the two support plates are arranged perpendicular to each other. The two auxiliary plates and the support plates form a cross-shaped structure.

[0016] As a further implementation method, the bottom of the auxiliary plate is fixedly arranged on the fixed plate, and an arc-shaped opening is also arranged at the top of the auxiliary plate.

[0017] As a further implementation method, the base pressing limit includes an L-shaped bending plate and a pressing block. Waist-shaped holes are arranged on both planes of the L-shaped bending plate. One of the waist-shaped holes is installed on the tooling workbench through a connecting piece, and the other waist-shaped hole is installed with the pressing block through a connecting piece. The pressing block is used to press the fixed block on the tooling workbench.

[0018] In a second aspect, the present invention also provides a use method of a welding tooling for a marine low-speed engine EGR stainless steel gas pipeline, including the following steps:

[0019] S1. Place the tooling workbench at a designated position and adjust the tooling workbench to the designated height for welding;

[0020] S2. According to the requirements of the pipeline drawing, install the first flange positioning device and the second flange positioning device corresponding to each other on the second guide rail and the third guide rail and adjust them to accurate positions, and perform pressing and positioning through the base pressing limit;

[0021] S3. Install the first elbow positioning bracket, the second elbow positioning bracket and the straight pipe positioning bracket corresponding to each other on the first guide rail and the second guide rail, and sequentially perform pressing and positioning through the base pressing limit;

[0022] S4. Install the gas pipeline onto the tooling in sequence according to the steps of flange - straight pipe - elbow - inclined pipe. Perform three-hole positioning between the flange and the first fixing bracket or the second fixing bracket, and tighten with bolts and nuts; adjust all pipeline and weld gaps, and keep the height of the welding position horizontal; use the upper and lower pressing limit devices for positioning to prevent the pipeline from rotating during the welding process;

[0023] S5. After the above work is completed, the weld welding work can be carried out.

[0024] Compared with the prior art, the advantages and positive effects of the present invention are:

[0025] The tooling workbench, guide rails, positioning frame and flange positioning device of the present invention cooperate with each other to form a precise positioning system. The guide rails provide precise sliding tracks and positioning references for the positioning frame and flange positioning device, so that they can be accurately installed and adjusted on the tooling; the elbow positioning frame and the straight pipe positioning frame can fit tightly with the pipeline through the arc-shaped opening of the support plate, and position the pipeline from multiple directions; the flange positioning device limits the flange circumferentially and axially through the ring and the fixing frame to ensure that the connection position of the flange and the pipeline is accurate. The synergistic effect of these structures enables the gas pipeline to be accurately positioned on the tooling before welding, effectively reducing the error of pipeline installation, improving the accuracy and consistency of the welded joints, and the multiple stable structures reduce welding defects caused by unstable tooling, reduce the rework rate, and improve welding efficiency and quality.

[0026] This invention securely secures the positioning frame and flange positioning device by combining upper and lower hold-down stops with base hold-down stops. The upper and lower hold-down stops, connected by threaded hold-down rods, flexibly clamp the pipeline, preventing movement or rotation during welding. The base hold-down stop utilizes an L-shaped bent plate and hold-down block to secure the positioning frame and flange positioning device to the workbench. Furthermore, the cross-shaped or crisscross-shaped structure of the elbow positioner and its auxiliary plate enhance stability at the elbow.

[0027] The guide rail design of this invention allows for the removable mounting of the positioning frame and flange positioning device. Combined with the clamping and limiting mounting hole array on the workbench base, the tooling allows for flexible adjustment of the positioning frame and flange positioning device, accommodating welding of gas pipelines of varying sizes, shapes, and layouts. The flange positioning device can be adjusted in angle and position to meet various flange-to-pipeline connection requirements; the liftable support legs adapt to varying workspaces and operator preferences. This high degree of versatility and flexibility reduces equipment investment costs and improves equipment utilization, making it suitable for welding various stainless steel gas pipelines for marine low-speed engine EGR systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0029] Figure 1 This is the overall structure diagram of the gas pipeline welding tool of the present invention;

[0030] Figure 2 This is a diagram of the base pressing and limiting structure of the present invention;

[0031] Figure 3 This is a structural diagram of the straight tube positioning frame of the present invention;

[0032] Figure 4 This is a structural diagram of the first elbow positioning frame of the present invention;

[0033] Figure 5 This is the structural diagram of the second elbow positioning bracket of the present invention.

[0034] In the figure: 1, tooling workbench; 2, first flange positioning device; 3, second flange positioning device; 4, first elbow positioning bracket; 5, second elbow positioning bracket; 6, straight pipe positioning bracket; 7, transverse strut; 8, base pressing limit; 9, first guide rail; 10, vertical strut; 11, pressing rod; 12, support leg; 13, L-shaped bending plate; 14, pressing block; 15, fixing plate; 16, support plate; 17, auxiliary plate. Detailed implementation manners

[0035] It should be noted that the following detailed descriptions are all illustrative and are intended to provide further explanations of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0036] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the present invention clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof;

[0037] Embodiment 1

[0038] This embodiment provides a welding tooling for the EGR stainless steel gas pipeline of a marine low-speed engine. As Figures 1 - 5 shown, it includes: a tooling workbench 1, a guide rail, an elbow positioning bracket, a straight pipe positioning bracket 6, a flange positioning device, and a base pressing limit 8; the guide rail is fixedly arranged on the tooling workbench 1, and both the elbow positioning bracket and the straight pipe positioning bracket 6 are arranged on the guide rail; the tooling workbench 1, the guide rail, the positioning bracket, and the flange positioning device cooperate with each other to form an accurate positioning system. The guide rail provides an accurate sliding track and positioning reference for the positioning bracket and the flange positioning device, enabling them to be accurately installed and adjusted on the tooling;

[0039] The elbow positioning frame includes a first elbow positioning frame 4 and a second elbow positioning frame 5. The first elbow positioning frame 4 is arranged at one end of the straight pipe positioning frame 6, and the second elbow positioning frame 5 is arranged at the other end of the straight pipe positioning frame 6. Both the first elbow positioning frame 4 and the second elbow positioning frame 5 are composed of support plates 16 with different heights, and the straight pipe positioning frame 6 is composed of support plates 16 with the same height. An arc-shaped opening is arranged at the upper end of the support plate 16, and a fixing plate 15 is arranged at the lower end. The fixing plate 15 is fixed on the tooling workbench 1 through the base pressing limit 8 to press and limit the height of the support plate 16. The elbow positioning frame and the straight pipe positioning frame 6 can be closely attached to the pipeline through the arc-shaped openings of the support plates 16 to position the pipeline from multiple directions. The flange positioning device limits the flange circumferentially and axially through the circular ring and the fixing frame to ensure the accurate connection position between the flange and the pipeline. The synergistic effect of these structures enables the gas pipeline to be accurately positioned on the tooling before welding, effectively reducing the installation error of the pipeline, improving the accuracy and consistency of the welded joints, and thus ensuring the installation quality and service performance of the gas pipeline.

[0040] As a further implementation method, it further includes: upper and lower pressing limits, which are arranged on one side of the tooling workbench 1. The upper and lower pressing limits are composed of a vertical strut 10, a horizontal strut 7, and a pressing rod 11. The lower end of the vertical strut 10 is fixedly arranged on the tooling workbench 1. One end of the horizontal strut 7 is fixedly arranged at the top of the vertical strut 10, and the other end of the horizontal strut 7 is threadedly connected to the pressing rod 11, enabling the pressing rod 11 to move vertically to press the pipeline and prevent the pipeline from moving or rotating during the welding process. The upper and lower pressing limits cooperate with the base pressing limit 8 to firmly fix the positioning frame and the flange positioning device on the tooling workbench 1, preventing them from shifting during the welding process, and further ensuring the welding accuracy of the pipeline.

[0041] As a further implementation method, the guide rail includes a first guide rail 9, a second guide rail, and a third guide rail; the second guide rail is arranged at one end of the first guide rail 9, and the third guide rail is arranged at the other end of the first guide rail 9; the straight pipe positioning frame 6 is slidably arranged on the first guide rail 9, the first elbow positioning frame 4 is slidably arranged on the second guide rail, and the second elbow positioning frame 5 is slidably arranged on the first guide rail 9; the flange positioning device includes a first flange positioning device 2 and a second flange positioning device 3. The first flange positioning device 2 is slidably arranged on the second guide rail, and the second flange positioning device 3 is slidably arranged on the third guide rail. The positioning frame and the flange positioning device are movably installed on the guide rail, and cooperate with the base pressing limit 8 installation hole array design on the tooling workbench 1, so that the welding tooling has strong versatility and flexibility; by adjusting the position of the base pressing limit 8 and the position of the positioning frame on the guide rail, it can adapt to the welding requirements of gas pipelines with different sizes, shapes, and layouts. The adjustable angle and position of the flange positioning device can meet the connection requirements of different types of flanges and pipelines.

[0042] As a further implementation method, the first flange positioning device 2 is composed of a first ring, a first fixing frame, and a mounting plate. The lower end of the mounting plate is slidably arranged on the fixing plate 15 and is positioned by the base pressing limit 8. The upper end of the mounting plate is fixedly connected to the first fixing frame. The first ring is arranged on the first fixing frame. There is an included angle with a set angle between the first fixing frame and the mounting plate; this included angle is designed according to the connection angle and installation requirements of the flange and the pipeline, so that the first ring can accurately position the flange. The inner diameter of the first ring is adapted to the outer diameter of the flange and can be sleeved on the flange to perform circumferential limit on the flange; at the same time, positioning holes are also arranged on the first fixing frame, corresponding to the bolt holes on the flange, and the three-hole positioning of the flange is realized through bolt and nut connection to ensure the accurate position of the flange during the welding process;

[0043] The second flange positioning device 3 is composed of a second ring and a second fixing frame. The lower end of the second fixing frame is installed on the fixing plate 15, and the second ring is installed at the upper end; specifically, the lower end of the second fixing frame is installed on the fixing plate 15 and fixed by the base pressing limit 8; the second ring is installed at the upper end. The structure and function of the second ring are similar to those of the first ring, and its inner diameter matches the outer diameter of the flange and can perform circumferential positioning on the flange.

[0044] As a further implementation, multiple said support plates 16 of the first elbow positioning frame 4 are parallel to each other, and an auxiliary plate 17 is arranged perpendicular to the multiple said support plates 16. The multiple support plates 16 and the auxiliary plate 17 are perpendicular to each other to form a cross-shaped structure, which is used to improve the stability of the positioning frame at the elbow of the gas pipeline; the auxiliary plate 17 not only increases the structural strength of the positioning frame at the elbow, but also can limit the elbow in the horizontal and vertical directions to prevent the elbow from displacing during the welding process. An arc-shaped opening is arranged at the upper end of the support plate 16, and the radian of the arc-shaped opening matches the outer surface radian of the elbow, which can better fit the elbow and improve the positioning accuracy.

[0045] As a further implementation, the second elbow positioning frame 5 also includes two mutually perpendicular auxiliary plates 17, and the two said support plates 16 are arranged perpendicular to each other. The two said auxiliary plates 17 and the support plates 16 form a grid-like structure; this structure further enhances the support and limiting ability of the positioning frame for the elbow, especially suitable for positioning elbows with complex angles and shapes. The bottom of the auxiliary plate 17 is fixedly arranged on the fixing plate 15, and an arc-shaped opening is also arranged at the top end, which acts together with the arc-shaped opening of the support plate 16 to position and fix the elbow from multiple directions, effectively improving the reliability of elbow positioning.

[0046] As a further implementation, the bottom of the auxiliary plate 17 is fixedly arranged on the fixing plate 15, and an arc-shaped opening is also arranged at the top end of the auxiliary plate 17, and its radian is consistent with the outer surface radian of the straight pipe, which can tightly wrap the straight pipe and provide stable support and positioning.

[0047] As a further implementation, the base pressing limit 8 includes an L-shaped bending plate 13 and a pressing block 14. Waist-shaped holes are arranged on both planes of the L-shaped bending plate 13. One of the waist-shaped holes is installed on the tooling workbench 1 through a connecting piece, and the other waist-shaped hole is installed with the pressing block 14 through a connecting piece. The pressing block 14 is used to press the fixing block on the tooling workbench 1.

[0048] A number of installation holes for the base pressing limit 8 are arranged in an array on the tooling workbench 1, which is used to adjust the position of the base pressing limit 8 to facilitate the installation and positioning of the positioning frame suitable for different sizes of pipelines; multiple support legs 12 are arranged at the lower part of the tooling workbench 1, and the support legs 12 are liftable legs, which are convenient to adjust the tooling workbench 1 to the indicated height for welding.

[0049] Embodiment 2

[0050] This embodiment provides a usage method of a welding tooling for a marine low-speed engine EGR stainless steel gas pipeline, including the following steps:

[0051] S1. Place the tooling workbench 1 at the designated position and adjust the tooling workbench 1 to the designated height for welding. Check whether the tooling workbench 1 is in a horizontal state by observing the spirit level on the tooling workbench 1 or using tools such as a spirit level. If it is found that the tooling workbench 1 is not horizontal, the height of each support leg 12 can be finely adjusted according to the adjustment method of the support leg 12, such as rotating the threaded adjustment assembly or operating the hydraulic adjustment device.

[0052] S2. Install the first flange positioning device 2 and the second flange positioning device 3 on the second guide rail and the third guide rail respectively according to the requirements of the pipeline drawing and adjust them to the precise position, and carry out pressing and positioning through the base pressing limit 8. Fix the mounting plate and the fixing frame firmly on the guide rail through the L-shaped bending plate 13 and the pressing block 14 of the base pressing limit 8.

[0053] S3. Install the first elbow positioning frame 4, the second elbow positioning frame 5 and the straight pipe positioning frame 6 on the first guide rail 9 and the second guide rail respectively, and carry out pressing and positioning through the base pressing limit 8 in sequence. Slide the first elbow positioning frame 4 and the second elbow positioning frame 5 along the guide rail to the appropriate position to ensure that the arc-shaped opening of the support plate 16 can closely fit the outer surface of the elbow. Install the straight pipe positioning frame 6 on the first guide rail 9 and adjust it according to the length and position requirements of the straight pipe. During the installation of the positioning frame, ensure that the installation of the positioning frame meets the requirements of the pipeline drawing. After adjusting the position of the positioning frame, firmly fix the fixing plate 15 of the positioning frame on the tooling workbench 1 through the base pressing limit 8, and tighten the connecting piece to make the pressing block 14 press the fixing plate 15 to prevent the positioning frame from moving during welding.

[0054] S4. Install the gas pipeline on the tooling in sequence according to the steps of flange - straight pipe - elbow - inclined pipe. Carry out three-hole positioning between the flange and the first fixing frame or the second fixing frame, and tighten it with bolts and nuts. Adjust the gaps of all pipelines and welds to keep the height of the welding position horizontal. Use the upper and lower pressing limit devices for positioning to prevent the pipeline from rotating during welding.

[0055] S5. After the above work is completed, the weld welding work can be carried out.

[0056] Although the specific implementation manners of the present invention are described above in conjunction with the drawings, it is not a limitation to the protection scope of the present invention. Those skilled in the art should understand that based on the technical solutions of the present invention, various modifications or deformations that can be made by those skilled in the art without creative efforts are still within the protection scope of the present invention.

Claims

1. A welding tooling for the EGR stainless steel gas pipeline of a marine low-speed engine, characterized in that, Including: A tooling workbench, a guide rail, an elbow positioning frame, a straight pipe positioning frame, and a base pressing limit; the guide rail is fixedly arranged on the tooling workbench, and both the elbow positioning frame and the straight pipe positioning frame are arranged on the guide rail; The elbow positioning frame includes a first elbow positioning frame and a second elbow positioning frame; the first elbow positioning frame is arranged at one end of the straight pipe positioning frame, and the second elbow positioning frame is arranged at the other end of the straight pipe positioning frame. Both the first elbow positioning frame and the second elbow positioning frame are composed of support plates with different heights, and the straight pipe positioning frame is composed of support plates with the same height. An arc-shaped opening is arranged at the upper end of the support plate, and a fixing plate is arranged at the lower end. The fixing plate is fixed on the tooling workbench through the base pressing limit.

2. The welding tooling for the EGR stainless steel gas pipeline of a marine low-speed engine according to claim 1, wherein It also includes: an upper and lower pressing limit, which is arranged on one side of the tooling workbench; the upper and lower pressing limit is composed of a vertical strut, a horizontal strut, and a pressing rod. The lower end of the vertical strut is fixedly arranged on the tooling workbench, one end of the horizontal strut is fixedly arranged at the top of the vertical strut, and the other end of the horizontal strut is threadedly connected with the pressing rod, so that the pressing rod can move vertically to realize the pressing of the pipeline.

3. A welding tooling for the EGR stainless steel gas pipeline of a marine low-speed engine as described in claim 1, characterized in that, The guide rail includes a first guide rail, a second guide rail, and a third guide rail; the second guide rail is arranged at one end of the first guide rail, and the third guide rail is arranged at the other end of the first guide rail; the straight pipe positioning frame is slidably arranged on the first guide rail, the first elbow positioning frame is slidably arranged on the second guide rail, and the second elbow positioning frame is slidably arranged on the first guide rail.

4. A welding tooling for the EGR stainless steel gas pipeline of a marine low-speed engine according to claim 3, characterized in that, A first flange positioning device is slidably arranged on the second guide rail, and a second flange positioning device is slidably arranged on the third guide rail.

5. A welding tooling for the EGR stainless steel gas pipeline of a marine low-speed engine according to claim 4, characterized in that, The first flange positioning device is composed of a first ring, a first fixing frame, and a mounting plate. The lower end of the mounting plate is slidably arranged on the fixing plate and is positioned through the base pressing limit. The upper end of the mounting plate is fixedly connected with the first fixing frame. The first ring is arranged on the first fixing frame, and there is an included angle with a set angle between the first fixing frame and the mounting plate; The second flange positioning device is composed of a second ring and a second fixing frame. The lower end of the second fixing frame is installed on the fixing plate, and the second ring is installed at the upper end.

6. The welding tooling for the EGR stainless steel gas pipeline of a marine low-speed engine according to claim 4, characterized in that, The multiple support plates of the first elbow positioning frame are parallel to each other, and an auxiliary plate is arranged perpendicular to the multiple support plates. The multiple support plates and the auxiliary plate are perpendicular to each other to form a cross-shaped structure, which is used to improve the stability of the positioning frame at the elbow of the gas pipeline.

7. A welding tooling for the EGR stainless steel gas pipeline of a marine low-speed engine according to claim 6, characterized in that The second elbow positioning frame also includes two mutually perpendicular auxiliary plates, and the two support plates are arranged perpendicular to each other. The two auxiliary plates and the support plates form a grid-like structure.

8. A welding tooling for the EGR stainless steel gas pipeline of a marine low-speed engine according to claim 7, characterized in that, The bottom of the auxiliary plate is fixedly arranged on the fixing plate, and an arc-shaped opening is also arranged at the top of the auxiliary plate.

9. A welding tooling for a marine low-speed engine EGR stainless steel gas pipeline as described in claim 1, characterized in that, The base pressing and limiting mechanism includes an L-shaped bending plate and a pressing block. Waist-shaped holes are provided on both planes of the L-shaped bending plate. One of the waist-shaped holes is installed on the tooling workbench through a connecting piece, and the other waist-shaped hole is installed with the pressing block through a connecting piece. The pressing block is used to press the fixed block on the tooling workbench.

10. A method for using a welding tooling for a marine low-speed engine EGR stainless steel gas pipeline according to any one of claims 1-9, characterized in that It includes the following steps: S1. Place the tooling workbench at the designated position and adjust the tooling workbench to the designated height for welding. S2. Install the first flange positioning device and the second flange positioning device on the second guide rail and the third guide rail respectively according to the requirements of the pipeline drawing, adjust them to the precise position, and perform pressing and positioning through the base pressing and limiting mechanism. S3. Install the first elbow positioning frame, the second elbow positioning frame and the straight pipe positioning frame on the first guide rail and the second guide rail respectively, and perform pressing and positioning through the base pressing and limiting mechanism in sequence. S4. Install the gas pipeline on the tooling in sequence according to the steps of flange - straight pipe - elbow - inclined pipe. Perform three-hole positioning between the flange and the first fixing frame or the second fixing frame, and tighten with bolts and nuts; adjust the gaps of all pipelines and welds, and keep the height of the welding position horizontal; use the upper and lower pressing and limiting devices for positioning to prevent the pipeline from rotating during the welding process. S5. After the above work is completed, the welding work of the weld can be carried out.

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