CN115582604A

CN115582604A - Gantry type multi-station welding system and method for large-diameter pipeline

Info

Publication number: CN115582604A
Application number: CN202211231819.XA
Authority: CN
Inventors: 范义焘; 邢海元; 杨旺; 刘凤林; 王福禄
Original assignee: Sinosteel Stainless Steel Pipe Technology Shanxi Co ltd
Current assignee: Sinosteel Stainless Steel Pipe Technology Shanxi Co ltd
Priority date: 2022-09-30
Filing date: 2022-09-30
Publication date: 2023-01-10

Abstract

The invention relates to a gantry type multi-station welding system and a welding method for large-diameter pipelines, which comprise a gantry frame, wherein a lifting table is arranged on the gantry frame, a linear guide rail is axially and fixedly arranged on the lifting table, a plurality of groups of fixed welding devices are fixedly arranged on the lifting table along the axis direction of the pipelines, a plurality of groups of movable welding devices are arranged on the linear guide rail in a sliding manner, and the groups of movable welding devices are fixed on the linear guide rail through locking mechanisms respectively after being well adjusted in position in a sliding manner. Through the arrangement, the plurality of groups of welding devices are arranged on the lifting table and the linear guide rail, so that a plurality of circular seams can be welded at the same time, and the production efficiency is improved; the linear guide rail is fixed on the lifting platform and can synchronously lift the lifting platform, so that the synchronous lifting control of the fixed welding device and the movable welding device is realized, and the operation is convenient. The movable welding devices can slide on the linear guide rail to adjust the position, so that the movable welding device can adapt to girth welding of pipelines with different lengths, is convenient to operate, and saves the cost.

Description

Large-diameter pipeline gantry type multi-station welding system and welding method

Technical Field

The invention belongs to the technical field of gantry type welding machines, and particularly relates to a gantry type multi-station welding system and a gantry type multi-station welding method for a large-diameter pipeline.

Background

The large-caliber stainless steel and special alloy circular welded pipe has good corrosion resistance, so that the special alloy circular welded pipe is suitable for special industries such as chemical industry, ships and the like. In the prior art, the welding of large-caliber stainless steel and special alloy pipelines is realized by adopting a gantry welding machine, the gantry welding machine is generally only provided with one group of welding devices, only one outer circular seam can be welded at one time, and the welding efficiency is low.

Disclosure of Invention

The invention aims to overcome the technical defect of low welding efficiency of a gantry welding machine on a pipeline in the prior art, and provides a gantry type multi-station welding system for a large-diameter pipeline.

In order to solve the problems, the invention provides a gantry type multi-station welding system for large-diameter pipelines, which comprises a gantry frame, wherein a lifting table is arranged on the gantry frame, a linear guide rail is fixedly arranged on the lifting table along the axial direction of the pipelines, a plurality of groups of fixed welding devices are fixedly arranged on the lifting table along the axial direction of the pipelines, a plurality of groups of movable welding devices are arranged on the linear guide rail in a sliding manner, and the plurality of groups of movable welding devices are fixed on the linear guide rail through locking mechanisms respectively after sliding to proper positions.

Optionally, the fixed welding devices are arranged into two groups, namely a first welding gun device and a second welding gun device; first welding set includes first welder subassembly, and first welder subassembly is fixed on the elevating platform, and second welder device includes electronic balladeur train and second welder subassembly, and electronic balladeur train is fixed on the elevating platform, and second welder subassembly slides and sets up on electronic balladeur train. Optionally, the movable welding device comprises an electric cross big sliding frame, an electric cross small sliding frame and a movable welding gun assembly, the movable welding gun assembly is slidably mounted on the electric cross small sliding frame, and the electric cross small sliding frame is slidably mounted on the electric cross big sliding frame

Optionally, the welding gun device further comprises a control system, and the first welding gun assembly, the second welding gun assembly, the electric sliding frame, the electric cross sliding frame and the movable welding gun assembly are respectively electrically connected with the control system. The control system controls the electric cross small sliding frame to slide on the electric cross large sliding frame along the transverse direction and the vertical direction, and the control system controls the movable welding gun assembly to slide on the electric cross small sliding frame along the transverse direction and the vertical direction.

Optionally, the lifting platform further comprises a fixing frame fixed on the ground, one end of the linear guide rail is fixedly connected to the lifting platform, and the other end of the linear guide rail is hung on the fixing frame through a spring balancer.

Optionally, the fixed frame comprises a frame formed by welding a plurality of vertical pipes and a plurality of transverse pipes, the upper end of the spring balancer is connected to the upper portion of the frame, and the lower end of the spring balancer is connected to one end of the linear slide rail.

Optionally, the welding assembly in the fixed welding device and the welding assembly in the movable welding device adopt a TIG welding assembly.

Optionally, the length of the pipe is 1.5 meters, 2 meters or 3 meters.

The invention also discloses a welding method, which comprises the gantry type multi-station welding system for the large-caliber pipeline, and comprises the following steps:

s1: the height of the lifting platform is adjusted through the control system to adapt to the caliber of the pipeline, and the positions of the first welding gun assembly, the electric sliding frame, the electric cross small sliding frame, the electric cross large sliding frame and the movable welding gun assembly are adjusted through the control system to adapt to the length of the pipeline, so that a group of welding devices are correspondingly arranged between every two adjacent pipelines;

s2: and controlling one or more groups of welding devices to weld the circular seams of the pipelines simultaneously by the control system.

Compared with the prior art, the invention has the beneficial effects that:

1. in the large-diameter pipeline gantry type multi-station welding system, the plurality of groups of welding devices are arranged on the lifting table and the linear guide rail, so that a plurality of circular seams can be welded at the same time, and the production efficiency is improved; the linear guide rail is fixed on the lifting platform and can synchronously lift the lifting platform, so that the synchronous lifting of the fixed welding device and the movable welding device is controlled, and the operation is convenient. The movable welding devices can slide on the linear guide rail to adjust the position, so that the movable welding device can adapt to girth welding of pipelines with different lengths, is convenient to operate, and saves the cost.

2. In the large-caliber pipeline gantry type multi-station welding system, three TIG welding devices are additionally arranged on the basis of the welding system of the original circular seam gantry welding machine, the original equipment is slightly changed, the production efficiency is improved, and the profit is increased.

3. In the large-caliber pipeline gantry type multi-station welding system, the arrangement of the spring balancer ensures that the linear guide rail keeps a horizontal position in the ascending and descending processes along with the lifting platform, and the movement stability is good.

4. In the large-caliber pipeline gantry type multi-station welding system, the circular seam welding of pipelines with different lengths can be realized by the matching of the linear guide rail, the electric large cross sliding frame and the electric small cross sliding frame, and the adaptability is good, so that the equipment cost is saved.

Drawings

FIG. 1 is a schematic view of a welding system according to the present embodiment;

FIG. 2 is a diagram illustrating the position of the welding gun assembly for welding a 1.5m pipe according to the present embodiment;

FIG. 3 is a diagram illustrating the position of the welding gun assembly for welding a 2-meter pipe according to the present embodiment;

fig. 4 is a positional relationship diagram of the welding gun assembly for welding a 3-meter pipe in the present embodiment.

Reference numerals: 1. a gantry; 11. a lifting platform; 12. a linear guide rail; 2. a first welding gun device; 21. a first weld gun assembly; 3. a second welding gun device; 31. a second weld gun assembly; 32. an electric carriage; 4. a third welding gun device; 41. a third torch assembly; 5. a fourth welding gun device; 51. a fourth torch assembly; 6. an electric cross big sliding frame; 61. an electric cross small carriage; 7. a fixed mount; 71. a spring balancer; 8. a pipeline.

Detailed Description

The invention is described in further detail below with reference to the figures and examples.

Examples

As shown in fig. 1-4, the embodiment provides a gantry type multi-station welding system for large-diameter pipelines, which includes a gantry 1, a lifting table 11 is arranged on the gantry 1, a linear guide rail 12 is fixedly arranged on the lifting table 11 along the axial direction of a pipeline 8, a plurality of groups of fixed welding devices are fixedly arranged on the lifting table 11 along the axial direction of the pipeline 8, a plurality of groups of movable welding devices are slidably arranged on the linear guide rail 12, and the plurality of groups of movable welding devices are respectively fixed on the linear guide rail 12 through a locking mechanism after sliding to proper positions.

Through the arrangement, the plurality of groups of welding devices are arranged on the lifting table 11 and the linear guide rail 12, so that a plurality of circular seams can be welded at the same time, and the production efficiency is improved; the linear guide rail 12 is fixed on the lifting platform 11 and can synchronously lift the lifting platform 11, so that the synchronous lifting of the fixed welding device and the movable welding device is controlled, and the operation is convenient. The plurality of groups of movable welding devices can slide on the linear guide rail 12 to adjust the position, so that the device can adapt to girth welding of pipelines 8 with different lengths, is convenient to operate and saves the cost. The locking mechanism may be locked using conventional locking members known in the art, such as fasteners such as bolts.

The pipe 8 of this embodiment can be a stainless steel or special alloy pipe.

In the large-caliber pipeline gantry type multi-station welding system of the embodiment, two groups of fixed welding devices are arranged, namely a first welding gun device 2 and a second welding gun device 3; the first welding gun device 2 comprises a first welding gun component 21, the first welding gun component 21 is fixed on the lifting platform 11, the second welding gun device 3 comprises an electric sliding frame 32 and a second welding gun component 31, the electric sliding frame 32 is fixed on the lifting platform 11, and the second welding gun component 31 is arranged on the electric sliding frame 32 in a sliding mode.

Through the setting, second welder subassembly 31 slides and sets up on electronic balladeur train 32, conveniently adjusts the position along the axis direction of pipeline 8 of first welder subassembly 21 to the pipeline 8 girth welding of adaptation different length, through the position of control system automatically regulated second welder subassembly 31, convenient operation saves the labour, and is efficient.

In the large-caliber pipeline gantry type multi-station welding system of the embodiment, specifically, the first welding gun device 2 is located on one side of the second welding gun device 3, the plurality of groups of movable welding devices are located on the other side of the second welding gun device 3, namely, the first welding gun device 2 is located at one end of the plurality of groups of welding devices, a first annular seam of the pipeline 8 is always welded, the welding of the pipelines 8 with different lengths can be adapted without transversely adjusting, and the cost is saved.

In the large-diameter pipeline gantry type multi-station welding system of the embodiment, the movable welding device comprises an electric cross large sliding frame 6, an electric cross small sliding frame 61 and a movable welding gun assembly, the movable welding gun assembly is slidably mounted on the electric cross small sliding frame 61, and the electric cross small sliding frame 61 is slidably mounted on the electric cross large sliding frame 6.

Through the setting, the position of the movable welding gun assembly is adjusted through the two sets of electric cross sliding frames, the range is wider, the precision is higher, and therefore the welding effect is better, and the welding gun assembly is suitable for welding of 8 circular seams of pipelines with different lengths. Specifically, in this embodiment, two sets of electric cross carriages are mounted on each movable welding gun assembly. Can increase the horizontal and fore-and-aft adjustment range of activity welder subassembly, activity welder subassembly shift position control is more accurate, makes things convenient for workman's operation, guarantees the welding effect. Specifically, the 1.5m and 2m circular seam welding can be simultaneously realized by adopting a left-right 1000mm stroke sliding frame and an upper-lower 500mm stroke sliding frame.

In the large-caliber pipeline gantry type multi-station welding system of the embodiment, the system further comprises a control system, and the first welding gun assembly 21, the second welding gun assembly 31, the electric sliding frame 32, the electric cross sliding frame 6, the electric cross sliding frame 61 and the movable welding gun assembly are respectively electrically connected with the control system. The control system controls the work of the first welding gun assembly 21, the second welding gun assembly 31 and the movable welding gun assembly, the control system controls the second welding gun assembly 31 to slide on the electric sliding frame 32, the control system controls the electric cross small sliding frame 61 to slide on the electric cross large sliding frame 6 along the transverse direction and the vertical direction, and the control system controls the movable welding gun assembly to slide on the electric cross small sliding frame 61 along the transverse direction and the vertical direction. In the large-diameter pipeline gantry type multi-station welding system of the embodiment, the gantry type multi-station welding system further comprises a fixing frame 7 fixed on the ground, one end of the linear guide rail 12 is fixedly connected to the lifting table 11, and the other end of the linear guide rail 12 is hung on the fixing frame 7 through a spring balancer 71.

Through the arrangement, the fixing frame 7 is used for suspending the linear guide rail 12, so that the gravity applied to the lifting platform 11 is reduced, the stress of the linear guide rail 12 is more balanced and stable, the lifting motion of the lifting platform 11 is more stable, and the welding stability of the welding device is improved.

In the large-diameter pipeline gantry type multi-station welding system of the embodiment, the fixing frame 7 comprises a frame formed by welding and enclosing a plurality of vertical pipes and a plurality of transverse pipes, the upper end of the spring balancer 71 is connected to the upper portion of the frame, and the lower end of the spring balancer 71 is connected to one end of a linear sliding rail.

Through the arrangement, the other end of the linear guide rail 12 is suspended on the fixed frame 7 through the arrangement of the spring balancer 71, so that the stress of the linear guide rail 12 is balanced, and the linear guide rail moves along with the synchronous lifting of the lifting table 11, the structure is simple, the synchronous lifting of a plurality of groups of welding devices is realized, the welding of pipelines 8 with different pipe diameters is adapted, the operation is convenient, and the stability of the linear guide rail 12 is improved.

Specifically, 150 × 100 square tube support frames are added on the other side of the lifting platform 11, and 120 × 120 square tubes are installed at the center end of the platform of the original gantry and used for supporting the other 3 sliding mechanical devices of the welding guns. A linear guide rail 12 is arranged at the end of the platform, so that the center line of the welding gun can be conveniently adjusted. The other side of the linear guide rail 12 is matched with a proper spring balancer 71, so that the linear guide rail 12 can be stably lifted up and down along with the lifting platform 11 on the basis of not increasing the weight of the original equipment.

In the gantry type multi-station welding system for the large-caliber pipeline, the welding assemblies in the fixed welding device and the movable welding device are all TIG welding assemblies.

In the large-caliber pipeline gantry type multi-station welding system of the embodiment, the movable welding devices are arranged into two groups, namely a third welding gun device 4 and a fourth welding gun device 5. The movable welding torch assembly of the third welding torch device 4 is the third welding torch assembly 41, and the movable welding torch assembly of the fourth welding torch device 5 is the fourth welding torch assembly 51.

In the large-diameter pipeline gantry type multi-station welding system of the embodiment, the length of the pipeline 8 is 1.5 meters, 2 meters or 3 meters.

Specifically, as shown in fig. 2, when the length of the pipe 8 is 1.5m, the first welding gun assembly 21, the second welding gun assembly 31, the third welding gun assembly 41 and the fourth welding gun assembly 51 are all spaced at a distance of 1.5m, and four girth welds can be welded simultaneously.

As shown in fig. 3, when the length of the pipe 8 is 2 meters, the distance between the second welding torch assembly 31 and the first welding torch assembly 21 is adjusted to 2 meters, the distance between the third welding torch assembly 41 and the second welding torch assembly 31 is adjusted to 2 meters, the fourth welding torch device 5 is adjusted to slide on the linear guide 12, and the position of the fourth welding torch assembly 51 on the electric cross carriage is adjusted until the distance between the fourth welding torch assembly 51 and the third welding torch assembly 41 is 2 meters, so that four welding seams can be welded simultaneously.

As shown in fig. 4, when the length of the pipe 8 is 3 meters, the distance between the third welding gun assembly 41 and the first welding gun assembly 21 is adjusted to 3 meters, the fourth welding gun device 5 is adjusted to slide on the linear guide rail 12, and the position of the fourth welding gun assembly 51 on the electric cross carriage is adjusted until the distance between the fourth welding gun assembly 51 and the third welding gun assembly 41 is 3 meters, and the first welding gun assembly 21, the third welding gun assembly 41 and the fourth welding gun assembly 51 are started, so that three welding seams can be welded simultaneously.

The welding method for the large-caliber stainless steel and special alloy pipeline 8 in the embodiment is as follows:

s1: the height of the lifting platform 11 is adjusted through the control system to adapt to the caliber of the pipeline 8, and the positions of the first welding gun assembly 21, the electric cross small carriage 61 and the second welding gun assembly 31 are adjusted through the control system to adapt to the length of the pipeline 8, so that a group of welding devices is correspondingly arranged between every two adjacent pipelines 8;

s2: one or more groups of welding devices are controlled by the control system to simultaneously weld the circular seams of the pipelines 8.

Specifically, this embodimentThree TIG welding systems are added on the basis of the welding system of the original circular seam gantry welding machine, and the welding system specifically comprises a high-frequency arc initiator, a monitoring system, a wire feeding system, a temperature control cold water tank and the like which are all connected with a control system. After the original welding system is transformed, the argon arc welding device has the functions of starting and stopping by one key, an operator can quickly select a welding process according to the condition of a workpiece, single-gun welding, double-gun welding or four-gun simultaneous welding and the like can be selected according to actual needs, and four welding gun assemblies can realize independent setting and independent action of parameters and the like. After the transformation of the embodiment, the processing capacity is improved, so that

For example, 8 welding seams of the product can be welded in one shift, and 1 finished product can be finished in two shifts.

Furthermore, the temperature control cold water tank consists of a high-efficiency condenser, a compressor, a fan motor, a temperature controller, a water detection sensor and other components, and is necessary corollary equipment for cooling a welding gun during automatic welding, such as welding in a plasma process and a high-load continuous state. The welding gun component is a WP27500A argon arc automatic welding gun which is mainly used for welding stainless steel, carbon steel, titanium, zirconium, alloy and other materials. The welding gun has the characteristics of good cooling effect, good electric arc compression effect, stable electric arc and the like, and is one of important fittings for obtaining good plasma welding quality.

The wire feeding system comprises an automatic wire feeder and a wire feeding support, wherein the wire feeder is driven by a direct current motor and is decelerated by a miniature speed reducer, a gear on an output shaft is meshed with gears with wire feeding wheels on two sides, a pressing wheel is arranged above the wire feeding wheels and is pressed by a spring lever, and the pressing force between the pressing wheel and the wire feeding wheels can be changed by rotating an eccentric wheel. The wire feeding device is suitable for the low-speed wire feeding requirements of PAW and TIG welding processes, corresponding wire feeding wheels are arranged according to the diameters of welding wires, and the diameters of the conveyable welding wires are phi 0.8, phi 1.0, phi 1.2 and phi 1.6.

The wire feeding support adopts a precise three-dimensional wire feeding support, the device is a functional matching part for feeding the optimal wire feeding angle into the molten pool during welding, and the device has the functions of convenient angle adjustment, small occupied space, simple welding gun connection and the like for TIG and PAW welding processes.

The electric cross sliding frame is matched with a power supply and a control system to realize the inching control of the electric arc height and the swing control of the welding gun component. The electric cross sliding frame is composed of two sliding plates which are connected in a cross mode, the screw rod is driven by the stepping motor to rotate when the electric cross sliding frame is adjusted and moved, the sliding plates are driven by the nuts to move, and parts such as a support plate, a welding gun seat, a welding gun, a multi-dimensional wire feeding support and the like are fixed on the moving block of the outer-layer cross sliding frame. The arc height adjusting carriage and the swinging carriage can be independently and separately installed and applied, and the horizontal and vertical positions of the welding gun can be adjusted by inching of a control button in the welding process.

A welding programmable control system is adopted, and the control system is a central system for completing the longitudinal seam/circular seam welding process. A stable and reliable Siemens PLC control technology platform is adopted. All control elements are arranged in a professional control box, a remote control programming panel adopts a centralized control layout, a full Chinese man-machine conversation interface realizes linkage control on all components of the system through programming, and the common function operation of the system can be realized by utilizing the remote control panel and a manual control box.

The high-frequency arc initiator is installed nearby, so that the arc initiation success rate of equipment is improved, tungsten clamping, tungsten electrode burning loss and the like are prevented, the manual operation intensity is reduced, and the purpose of improving the welding efficiency is realized. Meanwhile, welding defects caused by arc starting abnormity are reduced.

Economic benefits after implementation of the embodiment:

the original equipment processing capacity is

Stainless steel and special alloy with 5-40mm wall thickness, such as austenite, ferrite, duplex stainless steel, etc. The welding mode is P + T external welding, submerged arc internal and external welding. To be provided with

8 welding seams of the product are taken as an example, 1 welding seam is welded on the surface of the argon arc in one shift for 5 times, and the product is welded on one product in eight shifts.

After the embodiment is adopted, the production efficiency is improved by increasing the number of welding guns, wherein the welding mode P + T is changed into P + T + T + T.

After the method is adopted, the processing capacity is improved, and for example, 8 welding seams of the phi 3048 x 20 x 13500mm product are taken as an example, 4 welding seams can be welded in one time, and 1 finished product can be completed in two times. The full-automatic welding process of P + T + T + T is met, and independent operation can be realized.

Attached: see the calculation process for details.

And (3) calculating:

the annual capacity of the original unit is = ((diameter 3048-wall thickness 20) × wall thickness 20 × coefficient 0.02491 × length 13.5 ÷ 1000 ÷ 2 ÷ 8) × 300 days/year =685.8 tons.

The current unit annual capacity = ((diameter 3048-wall thickness 20) × wall thickness 20 × coefficient 0.02491 × length 13.5 ÷ 1000 ÷ 2) × 300 days/year =2754 tons.

Annual capacity increase capacity = existing unit capacity-original unit annual capacity =2068.2 ton.

Description of the invention: 0.02491 is a stainless steel physical weight coefficient, and according to 8 hours per day and 300 days per year, the processing profit is 5500 yuan/ton, the annual production increase profit = the annual capacity increase productivity × 5500 yuan-the wage of 1 operator is increased = 1137.5-10 ten thousand =1127.5 ten thousand yuan. Totaling: annual increase of productivity and profit: 1127.5 ten thousand yuan.

The embodiment improves the original equipment, builds a high-efficiency and high-quality intelligent large-caliber stainless steel and special alloy welded pipe production line, improves the production efficiency, reduces the production cost of enterprises, and creates economic benefits.

Claims

1. The utility model provides a heavy-calibre pipeline planer-type multistation welding system, a serial communication port, including portal frame (1), set up elevating platform (11) on portal frame (1), set up linear guide (12) along pipeline (8) axial fixity on elevating platform (11), the fixed welding set of a plurality of groups along the axis direction of pipeline (8) is gone up in elevating platform (11), it sets up a plurality of groups of movable welding set to slide on linear guide (12), a plurality of groups of movable welding set slide to fix on linear guide (12) through locking mechanical system respectively after the suitable position.

2. The gantry type multi-station welding system for the large-caliber pipelines according to claim 1, wherein the fixed welding devices are arranged in two groups, namely a first welding gun device (2) and a second welding gun device (3); first welder device (2) includes first welder subassembly (21), and first welder subassembly (21) is fixed on elevating platform (11), and second welder device (3) includes electronic balladeur train (32) and second welder subassembly (31), and electronic balladeur train (32) are fixed on elevating platform (11), and second welder subassembly (31) slides and sets up on electronic balladeur train (32).

3. The gantry type multi-station welding system for the large-caliber pipelines according to claim 2, wherein the movable welding device comprises an electric large cross carriage (6), an electric small cross carriage (61) and a movable welding gun assembly, the movable welding gun assembly is slidably mounted on the electric small cross carriage (61), and the electric small cross carriage (61) is slidably mounted on the electric large cross carriage (6).

4. The gantry type multi-station welding system for the large-caliber pipelines according to claim 3, further comprising a control system, wherein the first welding gun assembly (21), the second welding gun assembly (31), the electric carriage (32), the electric cross large carriage (6), the electric cross small carriage (61) and the movable welding gun assembly are respectively electrically connected with the control system.

5. The gantry type multi-station welding system for the large-diameter pipelines according to any one of claims 1 to 4, further comprising a fixed frame (7) fixed on the ground, wherein one end of the linear guide rail (12) is fixedly connected to the lifting table (11), and the other end of the linear guide rail (12) is suspended on the fixed frame (7) through a spring balancer (71).

6. The gantry type multi-station welding system for the large-caliber pipelines according to claim 5, wherein the fixed frame (7) comprises a frame formed by welding a plurality of vertical pipes and a plurality of transverse pipes, the upper end of the spring balancer (71) is connected to the upper part of the frame, and the lower end of the spring balancer (71) is connected to one end of a linear sliding rail.

7. Gantry-type multi-station welding system for large-caliber pipes according to any one of claims 1 to 4, wherein the length of the pipe (8) is 1.5, 2 or 3 meters.

8. A large-caliber pipeline welding method comprising the large-caliber pipeline gantry type multi-station welding system of any one of claims 4 to 7, and the method is characterized by comprising the following steps of:

s1: the height of the lifting platform (11) is adjusted through the control system to adapt to the caliber of the pipeline (8), and the positions of the second welding gun assembly (31), the electric sliding frame (32), the electric cross large sliding frame (6), the electric cross small sliding frame (61) and the movable welding gun assembly are adjusted through the control system to adapt to the length of the pipeline (8), so that a group of welding devices is correspondingly arranged between every two adjacent pipelines (8);

s2: one or more groups of welding devices are controlled by the control system to weld the circular seams of the pipelines (8) at the same time.