Automatic welding device for HDPE lining-concrete composite pipe joint

Abstract

The application discloses an automatic welding device for HDPE lining-concrete composite pipe joints and relates to an automatic welding device, which comprises an upper main body and a lower main body; the upper main body and the lower main body are rotationally connected through a rotating module; at least three variable-diameter modules are evenly installed on the periphery of the upper main body and the lower main body at the ends away from each other; a linear walking wheel is installed at the end of the variable-diameter module on the lower main body; a linear-circumferential walking wheel is installed at the end of the variable-diameter module on the upper main body; a welding module is installed in the upper main body, and a welding gun head in the welding module is installed on the linear-circumferential walking wheel; and a control module is installed in the lower main body. The application solves the problems of difficult welding of small-diameter pipes, low work efficiency, narrow work space and construction difficulties, and effectively improves the construction period of pipeline engineering.

Description

Technical Field

[0001] This invention relates to an automatic welding apparatus, and more specifically, to an automatic welding apparatus for HDPE-lined concrete composite pipe joints. Background Technology

[0002] Water supply and drainage pipelines are a crucial part of urban infrastructure, playing a vital role in ensuring people's production and daily life. HDPE (High-Density Polyethylene) lined concrete composite pipes are a new type of pipeline using high-density polyethylene (HDPE) liners as the inner lining and concrete pipe bodies as the pressure-bearing components. HDPE liners possess excellent water tightness and deformation adaptability, ensuring that water flow will not seep into the pipe body even after concrete cracking. Simultaneously, the HDPE liners prevent direct contact between water flow and the concrete pipe body, avoiding water corrosion and effectively improving the pipeline's durability. The pipe body is cast from economical and durable concrete, significantly increasing the ring stiffness of the pipe body with economical and reliable materials, thus possessing excellent load-bearing capacity and foundation adaptability. Therefore, HDPE-lined concrete composite pipes are a high-quality, low-cost pipeline with multiple excellent properties, showing great promise for widespread application.

[0003] Pipe joints are a crucial component of piping systems, and their reliability is a key factor in ensuring the safe operation of high-performance piping systems; they are also often the weakest link. Common pipe joints include socket joints and tongue-and-groove joints. These joints are prone to misalignment under conditions of significant foundation deformation or seismic shifts, leading to water seepage and safety risks. HDPE-lined concrete composite pipes utilize an HDPE lining with heat-fusion properties. Therefore, by heating the lining near the pipe joints, heat-fusion welding is performed to form a seamless joint, ensuring its reliability. However, current HDPE-lined concrete composite pipe joints require manual welding, which presents problems such as limited working space, complex workflow, high labor intensity, high cost, and low precision in manual welding. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an automatic welding device for HDPE-lined concrete composite pipe joints, which addresses the shortcomings of the existing technology and the problems of narrow pipe space, complex workflow, and high construction cost, and can effectively improve the reliability of pipe joint connection.

[0005] The present invention discloses an automatic welding device for HDPE-lined concrete composite pipe joints, comprising an upper body and a lower body; the upper body and the lower body are rotatably connected by a rotating module; at least three reducing modules are evenly installed around the periphery of each of the upper and lower bodies at their opposite ends; the reducing modules on the lower body are equipped with linear traveling wheels at their ends, and the reducing modules on the upper body are equipped with linear-circumferential traveling wheels at their ends; a welding module is installed in the upper body, and the welding torch head in the welding module is mounted on the linear-circumferential traveling wheels; a control module is installed in the lower body.

[0006] Preferably, the rotating module includes a motor, a second gear, and an internal gear disk; the motor is fixedly mounted on the end of the lower body via a mounting base, the output shaft of the motor is rotatably connected to the upper body, a first gear is fixedly mounted on the output shaft of the motor, the first gear meshes with the internal gear disk via the second gear, and the second gear is rotatably connected to the lower body via a mounting shaft.

[0007] Preferably, the variable diameter module includes a support frame, a lead screw slide, a hind limb frame, and a fore limb frame; the support frame is fixed to the upper body, one end of the support frame is slidably mounted in the lead screw slide, and a slider is rotatably mounted on the support frame, the slider being threadedly connected to the lead screw in the lead screw slide; the other end of the support frame is hinged to the middle of the hind limb frame, one end of the hind limb frame is hinged to the lead screw slide, and the other end of the hind limb frame is fixedly connected to the fore limb frame.

[0008] Preferably, a parallel frame is fixedly installed between the hind limb frame and the forelimb frame.

[0009] Preferably, at least one drive wheel assembly is fixedly installed on one side of both the hind limb frame and the forelimb frame.

[0010] Preferably, the welding module includes an air supply assembly and a material feeding assembly; a cavity is formed in the upper body, the air supply assembly is installed in the cavity, an air supply pipe is installed at one end of the cavity and communicates with it, and the air supply pipe is connected to the air supply interface of the welding gun head; the material feeding assembly includes a material feeding tray and a wire feeding mechanism; welding rods are wound on the material feeding tray, and the welding rods are conveyed to the welding gun head through the wire feeding mechanism and the transmission wheel assembly.

[0011] Preferably, the welding torch head is equipped with a heating wire for heating gas.

[0012] Preferably, all walking wheels are fixed to the end of the forelimb frame via pressure sensors.

[0013] Preferably, a camera is mounted on the end of the forelimb frame.

[0014] Preferably, the camera acquires real-time images of the weld position and transmits the real-time images to the control module. The control module calculates the weld center deviation value based on the real-time weld position and the target weld position, and corrects the weld position based on the weld center deviation value using a PID control algorithm, so that the welding torch head runs on the weld centerline.

[0015] Beneficial effects

[0016] The advantages of this invention are:

[0017] 1. Due to its variable diameter module, the automatic welding device can adapt to pipes of various diameters. Combined with the travel module and welding module, the automatic welding device can automatically weld HDPE layers inside the pipe, solving problems such as difficulty in welding small-diameter pipes, low work efficiency, and construction difficulties caused by limited working space, effectively improving the construction cycle of pipeline projects.

[0018] 2. The coordinated monitoring and control of pressure sensors, cameras, and control modules enable the automatic welding device to automatically identify the areas that need to be welded, and then complete the welding task through the rotating module, which greatly reduces the workload, lowers the difficulty of the work, improves the work efficiency, and saves a lot of labor costs and time. Attached Figure Description

[0019] Figure 1 This is a three-dimensional structural schematic diagram of the automatic welding device provided in an embodiment of the present invention.

[0020] Figure 2 This is a schematic diagram of the lower main structure of the automatic welding device provided in an embodiment of the present invention.

[0021] Figure 3 This is a schematic diagram of the welding module structure on one of the diameter-changing modules of the automatic welding device provided in an embodiment of the present invention.

[0022] Figure 3-A This is a detailed view of the welding module on one of the diameter-changing modules of the automatic welding device provided in an embodiment of the present invention.

[0023] Figure 4 This is a schematic diagram of the variable diameter module structure of the automatic welding device provided in the embodiment of the present invention.

[0024] Figure 5 This is a schematic diagram of the rotating module structure of the automatic welding device provided in an embodiment of the present invention.

[0025] Figure 6 This is a schematic diagram of the air supply component structure provided in an embodiment of the present invention.

[0026] Figure 7This is a schematic diagram of the linear-circumferential traveling wheel structure of the automatic welding device provided in the embodiment of the present invention.

[0027] Figure 8 This is a schematic diagram of the automatic welding process of the automatic welding device provided in the embodiment of the present invention.

[0028] The components include: 1. Lower main body; 2. Upper main body; 3. Rotating module; 31. Motor; 32. Gear II; 33. Internal gear plate; 4. Variable diameter module; 41. Screw slide; 42. Support frame; 43. Rear limb frame; 44. Front limb frame; 45. Parallel frame; 5. Linear travel wheel; 6. Linear-circumferential travel wheel; 7. Welding module; 71. Welding torch head; 72. Air supply assembly; 73. Feeding tray; 8. Control module; 9. Camera; 10. Transmission wheel assembly. Detailed Implementation

[0029] The present invention will be further described below with reference to embodiments, but this does not constitute any limitation on the present invention. Any limited modifications made by any person within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0030] See Figures 1-7 This invention discloses an automatic welding device for HDPE-lined concrete composite pipe joints, comprising an upper body 2 and a lower body 1. The upper body 2 and the lower body 1 are rotatably connected by a rotating module 3. During operation of the automatic welding device, the lower body 1 maintains a constant circumferential position, while the upper body 2 rotates under the drive of the rotating module 3. Specifically, the rotating module 3 includes a motor 31, a second gear 32, and an internal gear disc 33. The motor 31 is fixedly mounted on the end of the lower body 1 via a mounting base. The output shaft of the motor 31 is rotatably connected to the upper body 2. A first gear is fixedly mounted on the output shaft of the motor 31, and the first gear meshes with the internal gear disc 33 via the second gear 32. The second gear 32 is rotatably connected to the lower body 1 via a mounting shaft. When the rotating module 3 is operating, the motor 14 drives the internal gear disc 33 to rotate via the two gears. Since the internal gear disc 33 is fixedly connected to the upper body 2 of the automatic welding device, this drives the upper body 2 to rotate, allowing the welding torch head 71 mounted on the upper body 2 to perform circumferential welding on the pipe.

[0031] Three variable diameter modules 4 are evenly installed around the periphery of both the upper body 2 and the lower body 1 at their respective ends. The variable diameter module 4 serves as the support and drive component for the walking wheels and mainly includes a support frame 42, a lead screw slide 41, a hind limb frame 43, and a front limb frame 44. The support frame 42 is fixed to the upper body 2, and one end of the support frame 42 is slidably installed in the lead screw slide 41. A slider is rotatably installed on the support frame 42, and the slider is threadedly connected to the lead screw in the lead screw slide 41. The other end of the support frame 42 is hinged to the middle of the hind limb frame 43. One end of the hind limb frame 43 is hinged to the lead screw slide 41, and the other end of the hind limb frame 43 is fixedly connected to the front limb frame 44. When a change in diameter is required, the slider of the support frame 42 is controlled by the lead screw slide 41 to move along the lead screw axis, thereby changing the angle position of the support frame 42; the change in the angle of the support frame 42 will cause the rear limb frame 43 to rotate along the lead screw slide 41, thereby driving the front limb frame 44 to swing radially, thereby realizing the extension degree of the diameter changing module 4, thus adapting to different pipe diameters.

[0032] A linear travel wheel 5 is installed at the end of the variable diameter module 4 located on the lower main body 1, and a linear-circumferential travel wheel 6 is installed at the end of the variable diameter module 4 located on the upper main body 2. The linear travel wheel 5 is a travel wheel that can only move linearly along the inner wall of the pipe and is driven by a drive motor. The linear-circumferential travel wheel 6 can move linearly along the inner wall of the pipe and can also move circumferentially around the inner wall of the pipe. The six travel wheels installed on the main body together constitute the travel module, enabling the automatic welding device to move within pipes of different diameters. Through the support of the variable diameter module 4, each travel wheel is ensured to be in close contact with the pipe wall, thus realizing the movement of the automatic welding device within the pipe.

[0033] In this embodiment, a welding module 7 is installed in the upper body 2, and the welding gun head 71 in the welding module 7 is mounted on the linear-circumferential traveling wheels 6. Specifically, the welding module 7 includes an air supply assembly 72 and a feeding assembly. A cavity is formed in the upper body 2, and the air supply assembly 72 is installed in the cavity. An air supply pipe is installed at one end of the cavity and communicates with it. The air supply pipe is connected to the air supply interface of the welding gun head 71. The feeding assembly includes a feeding tray 73 and a wire feeding mechanism. Welding rods are wound on the feeding tray 73. At least one transmission wheel assembly 10 is fixedly installed on one side of both the rear limb frame 43 and the front limb frame 44. The welding rods are conveyed to the welding gun head 71 through the wire feeding mechanism and the transmission wheel assembly 10. The fan inside the air supply assembly 72 rotates, thereby supplying air to the welding gun head 71. The resistance wire inside the welding gun head 71 heats the air, making it a high-temperature gas that can soften high-density polyethylene (HDPE). At the same time, the feeding tray 73 feeds the welding rod to the welding gun head 71 for welding through the transmission wheel assembly 10.

[0034] The internal structure of the welding torch head 71 is as follows: Figure 3-A As shown, the welding torch head 71 includes a housing 711, a hot air channel 712, a welding rod guide tube 713, a heating wire 714, and a melting nozzle 715. The hot air channel 712 is arranged along the axis of the housing 711, with one end connected to an air supply pipe and the other end connected to the melting nozzle 715. The heating wire 714 is installed around the outlet end of the hot air channel 712 to heat the flowing hot air to 180°C~220°C. The welding rod guide tube 713 is inclinedly arranged on the side wall of the housing 711. The welding rod is guided by the transmission wheel assembly 10, passes through the welding rod guide tube 713, and extends to the outlet of the melting nozzle 715. During welding, the air supply assembly 72 pumps ambient air into the hot air channel 712, which is heated by the wire 714 to form high-temperature hot air that is ejected from the melting nozzle 715 to preheat the HDPE lining weld area. Simultaneously, the feeding tray 73 continuously feeds the welding rod into the welding rod guide tube 713 via the wire feeding mechanism and transmission wheel assembly 10. The welding rod is heated and melted by the high-temperature hot air at the outlet of the melting nozzle 715. Under the combined action of the hot air pressure and the subsequent welding rod thrust, the molten HDPE material is squeezed out and fills the HDPE lining gaps of the pipe joint, forming a sealing weld after cooling. The wire feeding speed and hot air temperature are controlled by the control module 8 in a closed loop according to the pipe diameter and welding speed, with the wire feeding speed ranging from 0.5 to 2.5 m / min.

[0035] In this embodiment, a control module 8 is installed in the lower main body 1, equipped with an STM32 control board, for closed-loop control of the movements of the aforementioned walking module, welding module 7, diameter changing module 4, and rotation module 3, thereby achieving the purpose of automatic welding. In addition, the control module 8 also includes conventional control circuits such as a motor drive unit, a vision acquisition unit, a data communication bus, and safety emergency stop and redundancy protection circuits. The motor drive unit controls the actions of the linear walking wheel 5, the lead screw slide 41, and the motor 31; the vision acquisition unit is responsible for detecting the weld position, geometry, and surface defects, such as identifying welding defects like insufficient fusion and off-center welding. When an abnormal state is detected, the STM32 main control chip automatically issues a stop command and sends back alarm information; the safety emergency stop and redundancy protection circuits are responsible for preventing the robot from going out of control under abnormal conditions, including overvoltage protection, self-locking braking, and a communication failure stop mechanism. When a control signal loss or equipment tipping is detected, the system immediately enters a safe state.

[0036] At the system architecture level of control module 8, it adopts a control architecture consisting of a decision layer, a control layer, and an execution layer. The core functions of the decision layer are weld seam extraction, trajectory planning, and welding area determination; the core function of the control layer is closed-loop control of the robot's walking speed, rotation angle, and welding torch heating; and the core function of the execution layer is to drive the motors and execute walking, rotation, welding, and diameter changing actions.

[0037] All the traveling wheels are fixed to the end of the front limb frame 44 by pressure sensors to detect the real-time pressure of the traveling wheels on the pipe wall. This data is transmitted back to the control module 8, which then controls the diameter-changing module 4 to change the diameter, ensuring tight contact between the traveling wheels and the pipe wall. Specifically, when the pressure is below a preset range, the screw of the lead screw slide 41 is controlled to rotate, causing the front limb frame 44 to extend outward and tighten the traveling wheels against the pipe wall. When the pressure is above the preset range, the screw of the lead screw slide 41 is controlled to rotate in the opposite direction, releasing excessive pressure from the traveling wheels on the pipe wall and preventing excessive clamping force from causing the device to jam. A camera 9 is installed at the end of the front limb frame 44 to record video of the environment around the linear-circumferential traveling wheels 6 and transmit the video data back to the control module 8 for monitoring the welding path and the welding quality of the weld.

[0038] Specifically, when the automatic welding device is working, such as Figure 8 As shown, the system is first powered on and started, followed by a self-test and zero-position reset by the control module 8. The control module 8 then controls the lead screw slide 41 to start, causing the variable diameter module 4 to unfold for pressure positioning, while simultaneously clamping the entire automatic welding device inside the pipe. The drive motor in the linear travel wheel 5 is activated, moving the automatic welding device to the first weld seam. Then, the camera 9 is activated to capture images. The control module 8 uses the captured images to locate the weld seam and plan the welding trajectory. Simultaneously, the control module 8 controls the rotation module 3 to reset, moving the welding torch head 71 to the welding starting point and aligning it.

[0039] During welding, welding module 7 is activated, simultaneously supplying hot air and welding rod to welding head 71, while rotation module 3 drives upper body 1 to rotate. During this process, camera 9 captures real-time images of the weld position and transmits these images to control module 8. Control module 8 calculates the weld center deviation value based on the real-time weld position and the target weld position, and uses a PID control algorithm to correct the weld position based on this deviation value, ensuring that welding torch head 71 operates on the weld centerline.

[0040] During the welding process, when a camera 9 detects that the corresponding welding torch head 71 deviates from the weld centerline, the control module 8 controls the lead screw slide 41 of the diameter-changing module 4 to make a small stroke adjustment (adjustment amount ≤ 5mm). By changing the unfolding angle of the rear limb frame 43 and the front limb frame 44, the welding torch head 71 is made to make a small displacement along the radial direction of the pipe, thereby realizing the independent position correction of the welding torch head 71 relative to the weld centerline.

[0041] To ensure that the new composite pipe automatic welding device can maintain high-precision welding tracking under different pipe diameters, the present invention uses the following PID control algorithm to adaptively adjust the device.

[0042] .

[0043] Where: U(k) is the speed regulation output of motor 31 in rotation module 3 (expressed as PWM duty cycle, range 0~100%), used to control the rotational angular velocity of upper body 2; e(k) is the circumferential pixel deviation value (unit: pixel) between the center line of welding torch 71 and the center line of weld seam at the kth sampling time, calculated by the vision acquisition unit of control module 8 from the real-time image captured by camera 9; when the center line of weld seam is located to the left of the image center, e(k)>0 (indicating that the welding torch head lags behind the weld seam), and when it is located to the right, e(k)<0 (indicating that the welding torch head leads the weld seam); K p (D) and K i (D) represents the proportionality and integral coefficients that vary with the pipe's inner diameter D; K d (D,P) are the differential coefficients that vary with the pipe inner diameter D and the contact pressure P of the traveling wheel.

[0044] Before welding begins, the automatic welding device is driven to move axially along the pipeline by linear travel wheels 5. Combined with visual positioning by camera 9, the welding torch head 71 is pre-aligned with the axial starting position of the weld seam. During welding, the welding torch head 71 only performs circumferential welding and does not involve axial position changes. Therefore, the PID control only needs to solve the circumferential angle tracking problem. If axial deviation occurs during welding due to pipeline ellipticity or installation errors, the control module 8 will pause welding, perform axial fine-tuning via linear travel wheels 5, and then restart welding.

[0045] During the welding process, camera 9 acquires real-time images of the weld seam at a period of 50ms and transmits them to control module 8. The visual acquisition unit of control module 8 extracts the position of the weld seam centerline and calculates its pixel deviation e(k) from the image centerline (i.e., the welding torch centerline). When e(k)>0 (weld seam is to the left, welding torch lags behind), the PID algorithm outputs U(k)>0, and control module 8 increases the PWM duty cycle of motor 31, increasing the rotational angular velocity of the upper body 2, so that welding torch 71 accelerates to catch up with the weld seam; when e(k)<0 (weld seam is to the right, welding torch 71 is ahead), the PID algorithm outputs U(k)<0, and the PWM duty cycle of motor 31 is reduced, so that welding torch 71 decelerates and waits for the weld seam to catch up. Through the above closed-loop control, it is ensured that welding torch (71) always runs on the weld seam centerline.

[0046] This embodiment employs a lookup table and online fine-tuning strategy to adaptively adjust the control parameters in the PID control algorithm. The specific implementation steps are as follows:

[0047] When the automatic welding device is placed into the working pipe and the diameter-changing module 4 is activated, the STM32 main control chip reads the stroke data of the lead screw slide 41 in real time. Based on the geometric relationship between the lead screw stroke and the linkage mechanism, the STM32 main control chip calculates the current pipe inner diameter value D. The PID parameter lookup table preset in the memory of the control module 8 calls the corresponding basic parameters according to the pipe inner diameter value D.

[0048] Control module 8 selects between a large-diameter mode (D > 1200 mm) and a small-diameter mode (D < 1200 mm) based on the pipe diameter D. When the working pipe is of a small diameter, the system's moment of inertia is relatively small, and the linear velocity of the welding torch head 71 is sensitive to changes in angular velocity. The PID control algorithm uses a weak proportional (smaller) PID control. Strong differential (larger) This prevents the welding torch from generating high-frequency oscillations near the weld centerline; when the working pipe is of a large diameter, the reducing module 4 is fully extended, and the system rigidity decreases, so the PID control algorithm adopts a strong proportional (larger) ratio. ), strong integral (appropriately increased) This provides sufficient torque to overcome frictional resistance and quickly eliminates the accumulated error caused by the stretching of the variable diameter module.

[0049] During the welding process, pressure sensors monitor the contact pressure between the wheels in the walking module and the pipe wall in real time. If significant pressure fluctuations are detected, indicating unstable walking or vibration, the differential coefficient in the PID algorithm will be adjusted. It will automatically increase according to the amplitude of pressure fluctuations, thereby enhancing the damping effect of the system, suppressing vibration, and realizing weld seam tracking.

[0050] After welding is completed, the automatic welding device moves to the next welding area to continue the welding operation.

[0051] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention, and these will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. An automatic welding device for HDPE-lined concrete composite pipe joints, characterized in that, It includes a lower body (1) and an upper body (2); the upper body (2) and the lower body (1) are rotatably connected by a rotating module (3), and at least three variable diameter modules (4) are evenly installed around the outer periphery of the upper body (2) and the lower body (1) at their respective ends. A linear walking wheel (5) is installed at the end of the variable diameter module (4) on the lower body (1), and a linear-circumferential walking wheel (6) is installed at the end of the variable diameter module (4) on the upper body (2); a welding module (7) is installed in the upper body (2), and the welding gun head (71) in the welding module (7) is installed on the linear-circumferential walking wheel (6); a control module (8) is installed in the lower body (1).

2. The automatic welding device for HDPE-lined concrete composite pipe joints according to claim 1, characterized in that, The rotating module (3) includes a motor (31), a second gear (32), and an internal gear disk (33). The motor (31) is fixedly installed at the end of the lower body (1) through a mounting base. The output shaft of the motor (31) is rotatably connected to the upper body (2). A first gear is fixedly installed on the output shaft of the motor (31). The first gear meshes with the internal gear disk (33) through the second gear (32). The second gear (32) is rotatably connected to the lower body (1) through a mounting shaft.

3. The automatic welding device for HDPE-lined concrete composite pipe joints according to claim 1, characterized in that, The variable diameter module (4) includes a lead screw slide (41), a support frame (42), a hind limb frame (43), and a forelimb frame (44). The support frame (42) is fixed on the upper body (2). One end of the support frame (42) is slidably installed in the lead screw slide (41), and a slider is rotatably installed on the support frame (42). The slider is threadedly connected to the lead screw in the lead screw slide (41). The other end of the support frame (42) is hinged to the middle of the hind limb frame (43). One end of the hind limb frame (43) is hinged to the lead screw slide (41), and the other end of the hind limb frame (43) is fixedly connected to the forelimb frame (44).

4. The automatic welding device for HDPE-lined concrete composite pipe joints according to claim 3, characterized in that, A parallel frame (45) is fixedly installed between the hind limb frame (43) and the forelimb frame (44).

5. The automatic welding device for HDPE-lined concrete composite pipe joints according to claim 3, characterized in that, At least one drive wheel assembly (10) is fixedly installed on one side of both the hind limb frame (43) and the forelimb frame (44).

6. The automatic welding device for HDPE-lined concrete composite pipe joints according to claim 5, characterized in that, The welding module (7) includes an air supply assembly (72) and a feeding assembly; a cavity is opened in the upper body (2), the air supply assembly (72) is installed in the cavity, and an air supply pipe connected to the cavity is installed at one end of the cavity. The air supply pipe is connected to the air supply interface of the welding gun head (71); the feeding assembly includes a feeding tray (73) and a wire feeding mechanism; welding rods are wound on the feeding tray (73), and the welding rods are conveyed to the welding gun head (71) through the wire feeding mechanism and the transmission wheel assembly (10).

7. An automatic welding device for HDPE-lined concrete composite pipe joints according to claim 6, characterized in that, The welding torch head (71) is equipped with a heating wire for heating gas.

8. The automatic welding device for HDPE-lined concrete composite pipe joints according to claim 3, characterized in that, All walking wheels are fixed to the end of the forelimb frame (44) via pressure sensors.

9. An automatic welding device for HDPE-lined concrete composite pipe joints according to claim 3, characterized in that, A camera (9) is mounted on the end of the forelimb frame (44).

10. An automatic welding device for HDPE-lined concrete composite pipe joints according to claim 9, characterized in that, The camera (9) acquires real-time images of the weld position and transmits the real-time images to the control module (8). The control module (8) calculates the weld center deviation value based on the real-time weld position and the target weld position, and corrects the weld position deviation based on the weld center deviation value using a PID control algorithm so that the welding torch head (71) runs on the weld center line.

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