CN118123313A - Pipeline welding robot and welding method thereof - Google Patents

Abstract

The invention relates to pipeline welding, and provides a pipeline welding robot and a welding method thereof, wherein the pipeline welding robot comprises a driving device, an angle measuring device connected with the driving device, and a welding device connected with the driving device; the driving device is arranged on the outer wall of the pipeline and moves circularly around the pipeline; the angle measuring device is used for measuring an included angle between a connecting line between adjacent welding spots of the outer walls of the adjacent pipelines and the axis of the pipeline; the welding device comprises an electric welding head and a rotating device; the rotating device drives the electric welding head to deflect by taking the outer wall of the end part of the pipeline as the center of a circle according to the angle data measured by the angle measuring device. According to the pipeline welding robot and the welding method thereof, corresponding welding angles can be adjusted according to different alignment degrees among pipelines, so that welding is firmer and safer.

Description

Pipeline welding robot and welding method thereof

Technical Field

The present invention relates to the technical field of pipeline welding, and in particular to a pipeline welding robot and a welding method thereof.

Background technique

Large or extra-large diameter metal pipes are often used to transport various types of water, gas, oil, etc. Due to the long transportation distance, a large number of pipes usually need to be connected by welding. In addition to manual welding, there is also more automated robot welding.

There are many types of robots used for welding, including welding robots driven by robotic arms installed indoors, which are mainly used for pre-assembly of pipes; there are also welding robots used outdoors (construction sites), which mainly adhere to the outer wall of the pipe and weld the gaps between pipes while performing circular motion on the outer wall of the pipe (adjacent pipes are not completely attached together during welding, and there is a certain gap between them, the size of which is determined by the material of the pipe and the wall thickness of the pipe).

In the actual welding process, although the pipeline needs to be aligned before welding, for large-diameter and heavy-weight pipelines, and when the installation path has a certain bend, it is sometimes not possible to completely align them. In this case, there will be a certain misalignment between the two adjacent pipelines. Although it is within the allowable range, it will still have a certain impact on welding. For example, when there is a misalignment (misalignment) between the welding points of adjacent pipelines, the volume of the melted metal at the ends of the two pipelines will be different, resulting in different connection areas of adjacent pipelines during pipeline welding. Desoldering, water leakage, and air leakage may occur later. For manual welding, manual operation can be adjusted according to actual conditions, such as tilting the angle of the welding head so that the welding head is aligned with the midpoint of the line connecting the ends of the pipelines, so that the melted volumes of the two pipelines are as consistent as possible, which is difficult for traditional welding robots to do.

Summary of the invention

The object of the present invention is to provide a pipeline welding robot and a welding method thereof, which can adjust the corresponding welding angle according to the different alignment degrees between pipelines, so as to make the welding more firm and safer.

The embodiment of the present invention is achieved through the following technical solutions: the pipeline welding robot of the present invention includes a driving device, an angle measuring device connected to the driving device, and a welding device connected to the driving device; the driving device is arranged on the outer wall of the pipeline and performs circular motion around the pipeline; the angle measuring device is used to measure the angle between the line between adjacent welding points on the outer wall of the pipeline and the axis of the pipeline; the welding device includes an electric welding head and a rotating device; the rotating device drives the electric welding head to deflect with the outer wall of the pipeline end as the center according to the angle data measured by the angle measuring device.

Furthermore, the angle measuring device includes a pair of limit plates in an inverted L shape and attached to the edge of the outer wall of the pipe, a roller arranged between the limit plate and the pipe, a first rack arranged on the side of the limit plate away from the pipe, an elastic member arranged on the side of the limit plate away from the pipe, a first connecting plate connected to the pair of elastic members, and a gear meshing with the pair of first racks, and an inclinometer connected to the gear; the first connecting plate is connected to the driving device; the outer wall of the roller is attached to the outer wall of the pipe.

Furthermore, the angle measuring device also includes a pair of limit strips arranged on one side of the first connecting plate close to the limit plate, and a long limit hole opened on the limit strip; the gear is provided with a central axis, and both ends of the central axis are arranged in the limit hole.

Furthermore, the elastic member includes a telescopic rod for connecting the limiting plate and the first connecting plate, and a spring sleeved on the telescopic rod; and a pair of telescopic rods are provided on the limiting plate.

Furthermore, the gear and the inclinometer are connected in sequence through a first connecting rod, a first universal joint, a telescopic joint, a second universal joint, and a second connecting rod; and the inclinometer and the first connecting plate are connected through a second connecting plate.

Furthermore, a pair of spring sheets are provided on one side of the inclinometer close to the pipe, and the plane where the spring sheets are located is perpendicular to the axis of the pipe; the spring sheets are thin metal sheets; and the pair of spring sheets are both clamped between the pair of pipes.

Furthermore, the rotating device includes an arc-shaped slide bar, a slide groove provided in the slide bar, an arc-shaped second rack slidably arranged in the slide groove, a driving tooth meshing with the second rack, a motor connected to the driving tooth, and a third connecting plate for connecting the slide bar and the driving device; the second rack is connected to the electric welding head, the plane where the slide bar is located coincides with the axis of the pipe, and the center of the slide bar is the center of a pair of adjacent outer walls of the pipe.

Furthermore, the driving device includes a housing, a pair of driving wheels arranged on one side of the housing close to the pipeline, and a power mechanism for driving the driving wheels to rotate; a strong magnet is arranged on the outer wall of the driving wheel.

The present invention also provides a pipeline welding method based on the pipeline welding robot, comprising the following steps:

(1) Install the driving device on the outer wall of one of the two pipes to be welded, and adjust its position so that it can move in a circle along the outer wall of the pipe;

(2) Install the angle measuring device at the front end of the driving device in the direction of movement so that it measures the angle between the line connecting adjacent welding points on the outer walls of adjacent pipes and the axis of the pipe;

(3) Install the welding device at the tail end of the driving device in the direction of movement, and align the welding head between two adjacent pipes;

(4) During welding, the angle measuring device measures the angle between the line connecting the outer walls of adjacent pipes and the axis of the pipe, and as the driving device makes a circular motion on the pipe, the recorded real-time changing angle is used as the motion trajectory of the welding head; the rear rotating device drives the welding head to make corresponding deflections according to the motion trajectory obtained by the angle measuring device, so that the axis of the welding head is always vertically aligned with the midpoint of the line connecting the adjacent pipe edges.

The technical solution of the embodiment of the present invention has at least the following advantages and beneficial effects: the pipeline welding robot and the welding method thereof of the present invention, when in use, installs a driving device on the outer wall of the pipeline so that the driving device can make a circular motion along the outer wall of the pipeline, and drives the angle measuring device and the welding device to make a circular motion along the outer wall of the pipeline while welding the pipeline; when the whole makes a circular motion, the angle measuring device first measures the angle between the connecting line between adjacent welding points on the outer wall of the adjacent pipeline and the pipeline axis (the angle can be positive or negative), and records the change of the angle in real time. Since there is a certain distance between the angle measuring device and the welding device, the electric welding in the welding device The angle of the head cannot be synchronized with the data measured by the angle measuring device in real time, but there is a certain delay. When the electric welding head moves to the corresponding welding point, the angle of its deflection is exactly the angle measured by the angle measuring device at this position (the initial angle of the electric welding head is perpendicular to the axis of the pipe). In this way, the electric welding head can be aligned with the midpoint of the line connecting the edges of the pipe in real time during welding. Then, when the two pipes are subjected to the high temperature of the electric welding head, the amount of melted parts of the two pipes is closer, and the welding area of the two pipes is closer, so that the final welding effect is better. In addition, the electric welding head automatically deflects during the whole process, and there is no need for manual complex calculations, so the welding efficiency is higher.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

FIG1 is a schematic structural diagram of a pipeline welding robot provided by an embodiment of the present invention when in use;

FIG2 is a schematic diagram of the structure of a pipeline welding robot provided by an embodiment of the present invention;

FIG3 is a schematic diagram of the internal structure of a pipeline welding robot provided by an embodiment of the present invention;

FIG4 is a schematic structural diagram of a viewing angle of a portion of an angle measuring device provided by an embodiment of the present invention;

FIG5 is a schematic structural diagram of two viewing angles of a portion of an angle measurement device provided by an embodiment of the present invention;

FIG6 is a schematic diagram of the structure of the inclinometer part provided by an embodiment of the present invention;

FIG7 is a schematic structural diagram of an angle R provided by an embodiment of the present invention;

FIG8 is a schematic structural diagram of a welding device provided by an embodiment of the present invention;

Icons: 10-driving device, 11-housing, 12-driving wheel, 20-angle measuring device, 21-limiting plate, 22-roller, 23-first connecting plate, 24-telescopic rod, 25-spring, 26-first rack, 27-gear, 28-first connecting rod, 29-first universal joint, 210-telescopic joint, 211-second universal joint, 212-second connecting rod, 213-angle meter, 214-limiting strip, 215-second connecting plate, 216-spring, 30-welding device, 31-slide bar, 32-slide groove, 33-second rack, 34-driving tooth, 35-motor, 36-electric welding head, 37-third connecting plate, 40-pipeline.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not require further definition and explanation in the subsequent drawings.

In the description of the present invention, it should be noted that if the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the product of the application is usually placed when used. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

Example 1

The following is further described in conjunction with specific embodiments. As shown in Figures 1 to 8, the pipeline welding robot of this embodiment includes a driving device 10, an angle measuring device 20 connected to the driving device 10, and a welding device 30 connected to the driving device 10; the driving device 10 is arranged on the outer wall of the pipeline 40 and performs a circular motion around the pipeline 40; the angle measuring device 20 is used to measure the angle between the line between adjacent welding points on the outer wall of adjacent pipelines 40 and the axis of the pipeline 40; the welding device 30 includes an electric welding head 36 and a rotating device; the rotating device drives the electric welding head 36 to deflect with the outer wall of the end of the pipeline 40 as the center according to the angle data measured by the angle measuring device 20. Specifically, when in use, the driving device 10 is installed on the outer wall of the pipe 40 so that it can make a circular motion along the outer wall of the pipe 40, and drive the angle measuring device 20 and the welding device 30 to make a circular motion along the outer wall of the pipe 40 while welding the pipe 40; when the whole makes a circular motion, the angle measuring device 20 first measures the angle between the connecting line between adjacent welding points on the outer wall of the adjacent pipe 40 and the axis of the pipe 40 (the angle can be positive or negative), as shown in FIG. 7, the angle is marked as R, and the change of the angle is recorded in real time. Since there is a certain distance between the angle measuring device 20 and the welding device 30, the angle of the electric welding head 36 in the welding device 30 cannot be the same as the angle measuring device 20. The data measured by the device 20 is synchronized in real time, but there is a certain delay. When the electric welding head 36 moves to the corresponding welding point, the angle of its deflection (the value is R) is exactly the angle measured by the angle measuring device 20 at this position (the initial angle of the electric welding head 36 is perpendicular to the axis of the pipe 40). In this way, during welding, the electric welding head 36 can be aligned with the midpoint of the edge line of the pipe 40 in real time. Then, when the two pipes 40 are subjected to the high temperature of the electric welding head 36, the amount of melting of the two is closer, and the welding area of the two is closer, so that the final welding effect is better. In addition, the electric welding head 36 automatically deflects during the whole process, and there is no need for manual complex calculations, so the welding efficiency is higher.

The angle measuring device 20 in this embodiment includes a pair of inverted L-shaped limiting plates 21 attached to the edge of the outer wall of the pipe 40, a roller 22 arranged between the limiting plate 21 and the pipe 40, a first rack 26 arranged on the side of the limiting plate 21 away from the pipe 40, an elastic member arranged on the side of the limiting plate 21 away from the pipe 40, a first connecting plate 23 connected to the pair of elastic members, and a gear 27 meshing with the pair of first racks 26, and an inclinometer 213 connected to the gear 27; the first connecting plate 23 is connected to the driving device 10; the outer wall of the roller 22 is attached to the outer wall of the pipe 40. Specifically, by attaching a pair of rollers 22 to the outer wall of a pair of pipes 40, when the driving device 10 drives the rollers 22 to make a circular motion around the outer wall of the pipes 40, due to the misalignment between the two pipes 40, the distance between the pair of rollers 22 and the axis of the pipes 40 is different (as shown in Figure 3, or called different heights), and due to the misalignment between the pipes 40, the rollers 22 will drive the limiter 21 to make an ups and downs motion with the first support plate as a fixed position, thereby driving the first rack 26 to make an ups and downs motion, when the misalignment distance (or angle) between the pipes 40 changes, the relative position between the pair of rollers 22 will change, and then drive the pair of first racks 26 to change the relative position, and if the pair of first racks 26 move relative to each other, then the gear 27 will be driven to rotate, and the rotation of the gear 27 can directly reflect the change of the angle, and directly transmit the change of the angle to the inclinometer 213, and the inclinometer 213 is used to measure and record the changed data. The inclinometer 213 can directly use the existing electronic related angle measuring device 20, or can use the principle similar to a gyroscope, which can be selected according to actual conditions. In addition, those skilled in the art may also select relevant data records and transfer modules according to actual needs.

The angle measuring device 20 in this embodiment further includes a pair of limiting bars 214 disposed on the first connecting plate 23 near the limiting sheet 21, and a long limiting hole formed on the limiting bar 214; the gear 27 is provided with a central axis, and both ends of the central axis are disposed in the limiting holes. Specifically, this can better limit the gear 27 to reciprocate only in the direction of the first rack 26 to prevent it from disengaging.

The elastic member in this embodiment includes a telescopic rod 24 for connecting the limiting plate 21 and the first connecting plate 23, and a spring 25 sleeved on the telescopic rod 24; a pair of telescopic rods 24 are provided on the limiting plate 21. Specifically, the roller 22 can be pressed against the outer wall of the pipe 40 by the spring 25.

The gear 27 and the inclinometer 213 in this embodiment are connected in sequence through the first connecting rod 28, the first universal joint 29, the telescopic joint 210, the second universal joint 211, and the second connecting rod 212; the inclinometer 213 and the first connecting plate 23 are connected through the second connecting plate 215. Specifically, since the roller 22 will always move during operation, and the inclinometer 213 is fixed, a universal joint and a telescopic joint 210 are required to connect the two.

In this embodiment, a pair of spring pieces 216 are provided on one side of the angle meter 213 close to the pipe 40, and the plane where the spring pieces 216 are located is perpendicular to the axis of the pipe 40; the spring pieces 216 are thin metal sheets; and the pair of spring pieces 216 are both clamped between the pair of pipes 40. Specifically, the spring pieces 216 are used to guide the device to move along the weld to prevent it from deflecting.

The rotating device in this embodiment includes an arc-shaped slide bar 31, a slide groove 32 provided in the slide bar 31, an arc-shaped second rack 33 slidably provided in the slide groove 32, a driving tooth 34 meshing with the second rack 33, a motor 35 connected to the driving tooth 34, and a third connecting plate 37 for connecting the slide bar 31 and the driving device 10; the second rack 33 is connected to the electric welding head 36, the plane where the slide bar 31 is located coincides with the axis of the pipe 40, and the center of the slide bar 31 is the center of the outer wall of a pair of adjacent pipes 40. Specifically, the initial position of the electric welding head 36 is perpendicular to the axis of the pipe 40, and the motor 35 will drive the second rack 33 to move in the slide groove 32 according to the data recorded by the inclinometer 213, and achieve the purpose of deflecting the corresponding angle by displacing a certain distance.

The driving device 10 in this embodiment includes a housing 11, a pair of driving wheels 12 disposed on one side of the housing 11 close to the pipe 40, and a power mechanism for driving the driving wheels 12 to rotate; a strong magnet is disposed on the outer wall of the driving wheel 12. Specifically, such a structure can directly use a structure already available on the market, which mainly uses the strong magnet on the outer wall of the driving wheel 12 to make the housing 11 fit on the pipe 40.

Example 2

This embodiment provides a pipeline welding method based on the pipeline welding robot of Embodiment 1, comprising the following steps:

(1) Install the driving device 10 on the outer wall of one of the two pipes 40 to be welded, and adjust its position so that it can move in a circle along the outer wall of the pipe 40;

(2) The angle measuring device 20 is installed at the front end of the driving device 10 in the moving direction so as to measure the angle between the line connecting the adjacent welding points on the outer walls of the adjacent pipes 40 and the axis of the pipe 40;

(3) The welding device 30 is installed at the rear end of the driving device 10 in the moving direction, and the welding head 36 is aligned between two adjacent pipes 40;

(4) When welding, the angle measuring device 20 measures the angle between the line connecting the outer walls of adjacent pipes 40 and the axis of the pipe 40, and as the driving device 10 makes a circular motion on the pipe 40, the recorded real-time changing angle is used as the motion trajectory of the welding head 36; the rear rotating device drives the welding head 36 to make corresponding deflections according to the motion trajectory obtained by the angle measuring device 20, so that the axis of the welding head 36 is always vertically aligned with the midpoint of the line connecting the adjacent edges of the pipe 40.

In summary, the pipeline welding robot and the welding method thereof of the present invention, when in use, installs the driving device 10 on the outer wall of the pipeline 40 so that it can make a circular motion along the outer wall of the pipeline 40, and drives the angle measuring device 20 and the welding device 30 to make a circular motion along the outer wall of the pipeline 40 while welding the pipeline 40; when the whole makes a circular motion, the angle measuring device 20 first measures the angle between the connecting line between adjacent welding points on the outer wall of adjacent pipelines 40 and the axis of the pipeline 40 (the angle can be positive or negative), and records the change of the angle in real time. Since there is a certain distance between the angle measuring device 20 and the welding device 30, the angle of the electric welding head 36 in the welding device 30 cannot be the same as that of the welding head 36 in the welding device 30. The data measured by the angle measuring device 20 is synchronized in real time, but there is a certain delay. When the electric welding head 36 moves to the corresponding welding point, the angle of its deflection is exactly the angle measured by the angle measuring device 20 at this position (the initial angle of the electric welding head 36 is perpendicular to the axis of the pipe 40). In this way, during welding, the electric welding head 36 can be aligned with the midpoint of the edge line of the pipe 40 in real time. Then, when the two pipes 40 are subjected to the high temperature of the electric welding head 36, the amount of melting of the two is closer, and the welding area of the two is closer, so that the final welding effect is better. In addition, the electric welding head 36 automatically deflects during the whole process, and there is no need for manual complex calculations, so the welding efficiency is higher.

The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims (9)

1. A pipeline welding robot, its characterized in that: comprises a driving device (10), an angle measuring device (20) connected with the driving device (10), and a welding device (30) connected with the driving device (10);

the driving device (10) is arranged on the outer wall of the pipeline (40) and performs circular motion around the pipeline (40);

The angle measuring device (20) is used for measuring an included angle between a connecting line between adjacent welding points of the outer wall of the pipeline (40) and the axis of the pipeline (40);

the welding device (30) comprises an electric welding head (36), and a rotating device; the rotating device drives the electric welding head (36) to deflect by taking the outer wall of the end part of the pipeline (40) as a circle center according to the angle data measured by the angle measuring device (20).

2. The pipe welding robot of claim 1, wherein: the angle measuring device (20) comprises a pair of limiting sheets (21) which are in an inverted L shape and are attached to the edge of the outer wall of the pipeline (40), a roller (22) arranged between the limiting sheets (21) and the pipeline (40), a first rack (26) arranged on one side, far away from the pipeline (40), of the limiting sheets (21), an elastic piece arranged on one side, far away from the pipeline (40), of the limiting sheets (21), a first connecting plate (23) connected with the pair of elastic pieces, a gear (27) meshed with the pair of first racks (26), and an angle meter (213) connected with the gear (27); the first connecting plate (23) is connected with the driving device (10);

The outer wall of the roller (22) is attached to the outer wall of the pipeline (40).

3. The pipe welding robot of claim 2, wherein: the angle measuring device (20) further comprises a pair of limiting strips (214) arranged on one side of the first connecting plate (23) close to the limiting sheet (21), and a strip-shaped limiting hole formed in the limiting strips (214); the gear (27) is provided with a central shaft, and two ends of the central shaft are arranged in the limiting holes.

4. The pipe welding robot of claim 2, wherein: the elastic piece comprises a telescopic rod (24) used for connecting the limiting piece (21) and the first connecting plate (23), and a spring (25) sleeved on the telescopic rod (24); a pair of telescopic rods (24) are arranged on the limiting piece (21).

5. The pipe welding robot of claim 2, wherein: the gear (27) is connected with the angle gauge (213) through a first connecting rod (28), a first universal joint (29), an expansion joint (210), a second universal joint (211) and a second connecting rod (212) in sequence; the angle gauge (213) is connected with the first connecting plate (23) through a second connecting plate (215).

6. The pipe welding robot of claim 2, wherein: a pair of elastic sheets (216) are arranged on one side, close to the pipeline (40), of the angle gauge (213), and the plane of each elastic sheet (216) is perpendicular to the axis of the pipeline (40); the elastic sheet (216) is a metal sheet; the pair of elastic sheets (216) are clamped between the pair of pipelines (40).

7. The pipe welding robot of claim 1, wherein: the rotating device comprises an arc-shaped sliding bar (31), a sliding groove (32) arranged in the sliding bar (31), an arc-shaped second rack (33) arranged in the sliding groove (32) in a sliding manner, a driving tooth (34) meshed with the second rack (33), a motor (35) connected with the driving tooth (34), and a third connecting plate (37) used for connecting the sliding bar (31) and the driving device (10);

the second rack (33) is connected with the electric welding head (36), the plane of the sliding bar (31) coincides with the axis of the pipeline (40), and the center of the sliding bar (31) is the center of the outer wall of a pair of adjacent pipelines (40).

8. The pipe welding robot of claim 1, wherein: the driving device (10) comprises a shell (11), a pair of driving wheels (12) arranged on one side of the shell (11) close to the pipeline (40), and a power mechanism for driving the driving wheels (12) to rotate;

the outer wall of the driving wheel (12) is provided with a strong magnet.

9. A pipe welding method based on the pipe welding robot according to any one of claims 1 to 8, comprising the steps of:

(1) The driving device is arranged on the outer wall of one of two pipelines to be welded, and the position of the driving device is adjusted to enable the driving device to do circular motion along the outer wall of the pipeline;

(2) The angle measuring device is arranged at the front end of the movement direction of the driving device, so that the angle measuring device measures the included angle between the connecting line between adjacent welding spots of the outer walls of adjacent pipelines and the axis of the pipeline;

(3) Installing a welding device at the tail end of the driving device in the moving direction, and enabling the electric welding head to be aligned between two adjacent pipelines;

(4) When welding work is carried out, the angle measuring device measures the included angle between the connecting line between the outer walls of adjacent pipelines and the axis of the pipeline, and the recorded included angle which changes in real time is used as the movement track of the electric welding head along with the circular movement of the driving device on the pipeline; the rear rotating device drives the electric welding head to deflect correspondingly according to the motion trail obtained by the angle measuring device, so that the axis where the electric welding head is positioned is always vertically aligned with the midpoint of the connecting line at the adjacent position of the edge of the pipeline.