Plastic-coated composite steel pipe welding device

Abstract

The invention relates to the field of steel pipe machining equipment, in particular to a plastic-coated composite steel pipe welding device which comprises a welding device body, the welding device body comprises a mounting base, a welding cavity used for containing a to-be-welded steel pipe is formed in the mounting base, and a sealing cover used for sealing the welding cavity is arranged at the mounting base. At least four groups of clamping mechanisms for clamping steel pipes to be welded are arranged in the welding cavity; a welding mechanism for welding the steel pipe to be welded is arranged in the welding cavity; a connector communicated with the welding cavity is arranged on the outer side wall of the mounting base, an exhaust pipe is connected to the connector, and the exhaust pipe is used for being connected with an air pump to pump out air in the welding cavity. Toxic gas can be limited in the welding cavity, high-concentration poisonous gas in the welding cavity is accurately and continuously pumped out, leakage of the poisonous gas can be avoided in combination with follow-up tail gas treatment equipment, and protection of welding personnel is well achieved.

Description

Technical Field

[0001] This invention relates to the field of steel pipe processing equipment, and more specifically, to a plastic-coated composite steel pipe welding device. Background Technology

[0002] Plastic-coated composite steel pipes, as a new type of anti-corrosion pipeline, use ordinary carbon steel pipes (such as seamless steel pipes and straight seam welded steel pipes) as the base material, with a polymer anti-corrosion coating (common materials include epoxy resin, polyethylene, polyvinyl chloride, etc.) applied to the inner or outer wall. The coating and base material are tightly bonded through processes such as high-temperature curing, electrostatic spraying, or dip coating. This type of steel pipe combines the high strength and rigidity advantages of carbon steel pipes with the excellent corrosion resistance, aging resistance, and scale resistance of polymer coatings. Simultaneously, the smooth coating surface effectively reduces fluid transport resistance. Therefore, it is widely used in water supply and drainage engineering, chemical fluid transportation, gas transportation, municipal pipeline network construction, and other fields, becoming an important alternative to traditional metal pipes, and market demand continues to grow. In the engineering application of plastic-coated composite steel pipes, pipe connection is one of the core processes. Welding, due to its high connection strength, good sealing performance, and strong adaptability, has become the main connection method in long-distance pipeline laying and complex pipeline network assembly. However, the welding process of plastic-coated composite steel pipes poses significant health and safety hazards: during welding operations, the high temperature of the electric arc (typically reaching 3000℃-6000℃) directly acts on the plastic coating at the pipe connection end, causing the polymer coating to undergo a thermal decomposition reaction. Taking the commonly used epoxy resin coating as an example, it decomposes at high temperatures to produce toxic volatile gases such as benzene, formaldehyde, and phenolic compounds; if the coating is made of polyvinyl chloride, it will further release highly corrosive and toxic gases such as hydrogen chloride. Currently, the industry primarily addresses the issue of toxic gases generated during the welding of plastic-coated composite steel pipes by employing simple protective measures such as workshop ventilation and wearing ordinary masks. However, workshop ventilation only achieves large-scale air circulation and cannot accurately capture high concentrations of toxic gases near the welding point, thus offering limited protection. Ordinary masks are insufficient to prevent small-molecule toxic gases from entering the body, failing to form an effective protective barrier. Therefore, the health hazards of toxic gases during the welding of plastic-coated composite steel pipes have become a key pain point restricting the safety of its engineering applications and hindering the standardization of the industry, urgently requiring technological innovation through specialized welding equipment to solve this problem. Summary of the Invention

[0003] To solve the above-mentioned technical problems, the present invention provides the following technical solution.

[0004] A welding device for plastic-coated composite steel pipes includes a welding device body, which includes a mounting base. The mounting base has a welding cavity for placing the steel pipe to be welded. The mounting base has a sealing cover for sealing the welding cavity. The welding cavity has at least four sets of clamping mechanisms for clamping the steel pipe to be welded. The welding cavity also has a welding mechanism for welding the steel pipe to be welded. The outer wall of the mounting base has a connector communicating with the welding cavity. An exhaust pipe is connected to the connector and is used to connect to an air pump to extract gas from the welding cavity.

[0005] As a preferred embodiment of the present invention, the clamping mechanism includes at least two first hydraulic push rods disposed at the bottom wall of the welding cavity and at least two first hydraulic push rods disposed at the sealing cover, and clamping rollers are rotatably disposed at the end of the piston rod of the first hydraulic push rod.

[0006] As a preferred embodiment of the present invention, a drive mechanism for cooperating with a clamping mechanism to rotate the steel pipe to be welded is provided at the center of the bottom end face of the welding cavity. The drive mechanism includes a second hydraulic push rod, and a roller mounting bracket is provided at the end of the piston rod of the second hydraulic push rod. A driven wheel is rotatably provided at the roller mounting bracket, and a drive motor for driving the driven wheel to rotate is provided at the roller mounting bracket. A first pulley is provided at the shaft of the drive motor. The axle of the driven wheel extends out of the roller mounting bracket, and a second pulley is provided at the end of the driven wheel extending out of the roller mounting bracket. A transmission belt is provided between the first pulley and the second pulley.

[0007] As a preferred embodiment of the present invention, the welding mechanism includes two sets of lead screw drive mechanisms, which are disposed at the sealing cover and arranged opposite to each other. Each set of lead screw drive mechanisms includes a base plate, which is bolted to the side wall of the sealing cover. A slide rail is provided on the base plate, and a sliding plate is slidably disposed above the slide rail. A slider that cooperates with the slide rail is provided on the bottom end face of the sliding plate. A lead screw is rotatably disposed on the base plate, and a lead screw nut that cooperates with the lead screw is provided at the bottom end of the sliding plate. A lead screw motor for driving the lead screw to rotate is also provided on the base plate. A welding gun is provided on the sliding plate of one set of lead screw drive mechanisms, and a welding rod is provided on the sliding plate of the other set of lead screw drive mechanisms.

[0008] As a preferred embodiment of the present invention, the sliding plate is provided with an adjustment mechanism for adjusting the vertical angle of the welding gun and welding rod. The adjustment mechanism includes two vertical plates, which are disposed on the sliding plate and arranged opposite to each other. A rotating column is rotatably provided between the two vertical plates. A mounting plate for placing the welding gun and welding rod is fixedly connected to the rotating column. One of the two vertical plates is provided with an adjustment motor for driving the rotating column to rotate.

[0009] As a preferred embodiment of the present invention, a nozzle is provided at the mounting plate where the welding torch is located, and an air inlet pipe is connected to the nozzle. The end of the air inlet pipe extends out of the welding chamber through the sealing cover, and a gas compressor is connected to the end of the air inlet pipe extending out of the welding chamber.

[0010] As a preferred embodiment of the present invention, the upper end of the mounting plate is bolted to a top cover plate, and the adjacent end faces of the mounting plate and the top cover plate are provided with arc-shaped grooves. The arc-shaped grooves on the mounting plate and the arc-shaped grooves on the top cover plate together form a mounting groove for mounting a welding gun, welding rod or nozzle.

[0011] As a preferred embodiment of the present invention, the clamping roller is made of rubber.

[0012] As a preferred embodiment of the present invention, one end of the sealing cover is hinged to the mounting base, and the other end of the sealing cover expands outward to form a sealing cover protrusion. The mounting base is provided with a mounting base protrusion corresponding to the sealing cover protrusion, and the sealing cover protrusion and the mounting base protrusion are bolted together.

[0013] The beneficial effects of this invention are as follows: 1. This invention forms a closed welding space through a sealing cover and a welding cavity, which confines toxic gases within the welding cavity and prevents them from spreading to the working environment. Furthermore, by accurately and continuously extracting high-concentration toxic gases from the welding cavity, combined with subsequent exhaust gas treatment equipment, leakage of toxic gases can be prevented, thus providing better protection for welding personnel.

[0014] 2. This invention clamps the steel pipe from multiple radial points, and the rubber material avoids scratching the steel pipe. At the same time, its rotation characteristics are adapted to the rotation requirements of the steel pipe, solving the problems of traditional positioning methods that easily scratch the steel pipe when clamping it and that the steel pipe easily shifts when rotating it.

[0015] 3. This invention can deliver inert protective gas to the welding area when welding steel pipes, avoid oxidation of the weld pool, solve the problem of reduced joint strength caused by welding oxidation, and improve the corrosion resistance and anti-aging performance of the welded joint. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the welding device for plastic-coated composite steel pipes in Example 1; Figure 2 This is a cross-sectional view of the plastic-coated composite steel pipe welding device in Example 1; Figure 3 This is a schematic diagram of the roller mounting bracket in Example 1; Figure 4 This is a cross-sectional view of the plastic-coated composite steel pipe welding device in Example 1; Figure 5 This is a schematic diagram of the lead screw drive mechanism in Example 1; Figure 6This is an exploded view of the screw drive mechanism in Example 1; Figure 7 This is a schematic diagram of the mounting plate and the top cover plate in Example 1.

[0017] The attached figures are labeled as follows: 130. Protrusion; 140. Connector; 210. Exhaust pipe; 220. Welding cavity; 230. First hydraulic push rod; 240. Clamping roller; 250. Second hydraulic push rod; 250. Roller mounting bracket; 310. Driven wheel; 320. Drive motor; 330. First pulley; 340. Second pulley; 350. Transmission belt; 410. Base plate; 420. Welding torch; 430. Welding rod; 510. Slide rail; 520. Sliding plate; 530. Slider; 540. Lead screw motor; 610. Lead screw; 620. Lead screw nut; 630. Vertical plate; 640. Rotating column; 650. Mounting plate; 660. Adjusting motor; 670. Nozzle; 680. Air inlet pipe; 710. Top cover plate; 720. Arc-shaped groove; 730. Mounting slot. Detailed Implementation

[0018] To further understand the content of this invention, a detailed description of the invention will be provided in conjunction with the accompanying drawings and embodiments. It should be understood that the embodiments are merely illustrative and not limiting of the invention.

[0019] Example 1, as Figures 1-7 As shown, this embodiment provides a plastic-coated composite steel pipe welding device, which includes a welding device body 100. The core bearing component of the welding device body 100 is a mounting base 110. A welding cavity 210 for accommodating and positioning the steel pipe to be welded is provided inside the mounting base 110. The steel pipe to be welded can be placed in the welding cavity 210 to complete the welding operation.

[0020] To achieve closed collection of toxic gases during welding, a sealing cover 120 for sealing the welding cavity 210 is fitted at the mounting base 110. One end of the sealing cover 120 is hinged to the mounting base 110, and the other end expands outward to form a sealing cover protrusion 121. The mounting base 110 has an integrally formed mounting base protrusion 111 corresponding to the position of the sealing cover protrusion 121. By inserting bolts between the sealing cover protrusion 121 and the mounting base protrusion 111, the sealing cover 120 and the mounting base 110 can be tightly fixed, thereby making the welding cavity 210 a closed space.

[0021] Meanwhile, a connector 130 communicating with the inside of the welding cavity 210 is fixedly provided on the outer wall of the mounting base 110. An exhaust pipe 140 is sealed and connected to the end of the connector 130 away from the mounting base 110. The free end of the exhaust pipe 140 is used to connect to an external air pump (not shown in the figure) so as to extract the toxic gas generated by welding in the welding cavity 210 through the negative pressure of the air pump.

[0022] To ensure the stability of the steel pipe to be welded during the welding process, the welding cavity 210 is provided with at least 4 sets of clamping mechanisms for clamping and positioning the steel pipe to be welded; each set of clamping mechanisms includes at least 2 first hydraulic push rods 220 disposed on the bottom wall of the welding cavity 210, and at least 2 first hydraulic push rods 220 disposed on the inner side wall of the sealing cover 120 (the first hydraulic push rods 220 on the bottom wall and the sealing cover are distributed vertically in correspondence).

[0023] A clamping roller 230 is rotatably provided at the end of the piston rod of each first hydraulic push rod 220, and the clamping roller 230 is made of rubber. The use of rubber clamping roller 230 can avoid scratching the outer surface of the steel pipe to be welded during the clamping process. At the same time, the rotatably provided clamping roller 230 can adapt to the rotation requirements of the steel pipe to be welded.

[0024] Combine Figure 3 As shown, in order to achieve circumferential welding of the steel pipe to be welded (to ensure the uniformity of the weld circumference), a driving mechanism is provided at the center of the bottom end face of the welding cavity 210 for cooperating with the clamping mechanism to drive the steel pipe to be welded to rotate; the driving mechanism includes a vertically arranged second hydraulic push rod 240, the cylinder of the second hydraulic push rod 240 is fixed to the bottom wall of the welding cavity 210, and the top end of its piston rod is fixedly connected to a roller mounting bracket 250. A driven wheel 310 is rotatably mounted on the top of the roller mounting bracket 250, and a drive motor 320 for driving the driven wheel 310 to rotate is fixedly mounted on the side wall of the roller mounting bracket 250. A first pulley 330 is connected to the output shaft of the drive motor 320. One end of the axle of the driven wheel 310 passes through and extends out of the side wall of the roller mounting bracket 250, and the extended end is keyed to a second pulley 340. A transmission belt 350 for power transmission is sleeved between the first pulley 330 and the second pulley 340. The operation of the drive motor 320 can drive the driven wheel 310 to rotate, thereby driving the steel pipe to be welded to rotate around its own axis.

[0025] The welding cavity 210 is provided with a welding mechanism for welding the steel pipe to be welded. The welding mechanism includes two sets of screw drive mechanisms with the same structure and arranged opposite each other. Both sets of screw drive mechanisms are fixedly arranged on the inner side wall of the sealing cover 120 (symmetrically distributed with respect to the central axis of the welding cavity 210).

[0026] Combine Figures 4-6 As shown, each set of lead screw drive mechanisms includes a base plate 410, which is fixedly connected to the inner wall of the sealing cover 120 by bolts, serving as the mounting base for the lead screw drive mechanism; a slide rail 510 is provided at the base plate 410, and the slide rail 510 is fixedly disposed on the top surface of the base plate 410 along the length direction of the base plate 410; a sliding plate 520 is provided above the slide rail 510, and a slider 530 adapted to the slide rail 510 is fixedly connected to the bottom end face of the sliding plate 520 by bolts, and the slider 530 slides with the slide rail 510, so that the sliding plate 520 can slide along the slide rail 510. The slide plate 520 moves back and forth along its length. A lead screw 610 is also provided at the base plate 410. The lead screw 610 is rotatably supported on the top surface of the base plate 410 and is arranged parallel to the slide rail 510. A lead screw nut 620 is bolted to the bottom end face of the sliding plate 520 and is threadedly engaged with the lead screw 610. A lead screw motor 540 is provided at one end of the base plate 410. Its output shaft is connected to one end of the lead screw 610 through a coupling (not shown) to drive the lead screw 610 to rotate. In turn, the sliding plate 520 is moved by the threaded engagement between the lead screw 610 and the lead screw nut 620.

[0027] One set of the lead screw drive mechanism has a sliding plate 520 at its bottom end fixed with a welding torch 420 for outputting a welding arc, and another set of the lead screw drive mechanism has a sliding plate 520 at its bottom end fixed with a welding rod 430 for providing welding filler material, which can be adjusted by the coordinated action of the two sets of lead screw drive mechanisms to adapt to the welding requirements of steel pipes of different specifications.

[0028] To accommodate different welding angle requirements, each set of lead screw drive mechanisms is equipped with an adjustment mechanism at the sliding plate 520 for vertically adjusting the angle of the welding torch 420 or welding rod 430. The adjustment mechanism includes two opposing vertical plates 630, both vertically fixed to the bottom surface of the sliding plate 520 by bolts, and a rotating column 640 rotatably connected between the two vertical plates 630. A mounting plate 650 for mounting the welding torch 420 or welding rod 430 is bolted to the outer wall of the rotating column 640, and an adjustment motor 660 for driving the rotation of the rotating column 640 is fixedly mounted on the outer wall of one of the vertical plates 630. The output shaft of the adjustment motor 660 is connected to one end of the rotating column 640. By adjusting the forward and reverse rotation of the adjustment motor 660, the rotating column 640 can rotate around its own axis, thereby adjusting the angle of the mounting plate 650 and the welding torch 420 or welding rod 430 on it in the vertical direction.

[0029] Welding protection structure: A nozzle 670 is fixedly mounted on the bottom surface of the mounting plate 650 on which the welding torch 420 is installed by bolts. The jet direction of the nozzle 670 is towards the welding end of the welding torch 420. The air inlet end of the nozzle 670 is sealed and connected to an air inlet pipe 680. The free end of the air inlet pipe 680 passes through and extends out of the sealing cover 120. This extended end is used to connect to an external gas compressor. An inert protective gas (such as argon) can be supplied to the nozzle 670 through the gas compressor to prevent the welding area from being oxidized and improve the welding quality.

[0030] Combine Figure 7 As shown, to facilitate the disassembly and maintenance of the welding torch 420, welding rod 430, or nozzle 670, the upper end of the mounting plate 650 is detachably connected to a top cover plate 710 by bolts; the adjacent end faces of the mounting plate 650 and the top cover plate 710 (i.e., the top surface of the mounting plate 650 and the bottom surface of the top cover plate 710) are both provided with arc-shaped grooves 720. The arc-shaped grooves 720 at the mounting plate 650 and the arc-shaped grooves 720 at the top cover plate 710 together form a mounting groove 730 for mounting the welding torch 420, welding rod 430, or nozzle 670. The above components can be quickly replaced or maintained by disassembling the top cover plate 710.

[0031] In use, the operator opens the sealing cover 120 (remove the bolts between the sealing cover protrusion 121 and the mounting base protrusion 111, and flip it open around the hinge point); then, place the two plastic-coated composite steel pipes (not shown) to be welded together in the welding cavity 210, aligning the welding joints of the two steel pipes with the center of the welding cavity 210; close the sealing cover 120, and re-fix the sealing cover protrusion 121 and the mounting base protrusion 111 with bolts to form a closed space in the welding cavity 210; connect the exhaust pipe 140 to the air pump, and connect the air inlet pipe 680 to the gas compressor. Activate all first hydraulic push rods 220, causing their piston rods to extend and drive the clamping rollers 230 to approach the outer wall of the steel pipe to be welded, until the corresponding upper and lower clamping rollers 230 are in close contact with the outer wall of the steel pipe, thus achieving radial positioning and clamping of the steel pipe to be welded; activate the second hydraulic push rod 240, causing its piston rod to extend and drive the roller mounting bracket 250 and driven wheel 310 to move upward, until the top surface of the driven wheel 310 is in close contact with the outer wall of the steel pipe to be welded. At this time, the driven wheel 310 and the clamping rollers 230 together form a support and rotational constraint for the steel pipe.

[0032] Welding angle adjustment: Start the adjusting motor 660, which drives the rotating column 640 to rotate, thereby adjusting the angle of the mounting plate 650 so that the welding end of the welding torch 420 and the filling end of the welding rod 430 are aligned with the interface of the steel pipe to be welded. After the preset welding angle is reached, turn off the adjusting motor 660. Start the two sets of lead screw motors 540, which drive the lead screw 610 to rotate. Through the lead screw nut 620, the sliding plate 520 moves along the slide rail 510 until the welding torch 420 and the welding rod 430 move to the welding start position. At the same time, start the welding torch 420 and drive the... Motor 320 and gas compressor: Welding torch 420 outputs an electric arc, welding rod 430 provides filler material, and welding operation begins; drive motor 320 drives driven wheel 310 to rotate through first pulley 330, transmission belt 350 and second pulley 340. Driven wheel 310 drives the steel pipe to be welded to rotate slowly around its own axis to realize circumferential welding of the steel pipe joint; gas compressor delivers inert protective gas to nozzle 670 through air inlet pipe 680. Nozzle 670 sprays protective gas towards the welding area to isolate air and prevent oxidation of the weld pool.

[0033] Simultaneously with the start of welding, the vacuum pump is activated, creating negative pressure within the welding chamber 210 through the exhaust pipe 140 and connector 130. This continuously extracts toxic gases (such as benzene, formaldehyde, and hydrogen chloride) generated during the high-temperature decomposition of the plastic coating during welding, transporting them to subsequent exhaust gas treatment equipment for purification to prevent leakage. After welding is completed, the welding torch 420, welding rod 430, drive motor 320, gas compressor, and vacuum pump are sequentially shut off. The first and second hydraulic push rods 220 are then activated in reverse to release the steel pipe to be welded. The sealing cap 120 is then opened to remove the welded steel pipe, completing one welding operation.

[0034] The beneficial effects that the plastic-coated composite steel pipe welding device in this embodiment can achieve through the above technical solution are as follows: 1. The high temperature generated during the welding of plastic-coated steel pipes causes toxic gases to diffuse, endangering the health of welders. Existing workshop ventilation and ordinary masks provide poor protection. In this embodiment, the plastic-coated composite steel pipe welding device forms a closed welding space through the sealing cover 120 and the welding chamber 210, confining the toxic gases within the welding chamber 210 and preventing them from spreading to the working environment. Furthermore, the connector 130, exhaust pipe 140, and air pump achieve negative pressure active extraction, accurately and continuously extracting the high concentration of toxic gases from the welding chamber 210. Combined with subsequent exhaust gas treatment equipment, leakage of toxic gases can be avoided, eliminating the risk of damage to the respiratory tract and organs of welders, thus achieving better protection for welders.

[0035] 2. In this embodiment, the plastic-coated composite steel pipe welding device clamps the steel pipe from multiple radial points using clamping rollers 230 distributed on the upper and lower sides. The rubber material prevents scratching the steel pipe, and the rotation characteristics are adapted to the rotation requirements of the steel pipe, solving the problems of easy scratching of the steel pipe when clamping it and easy displacement of the steel pipe when rotating it in the traditional positioning method.

[0036] 3. In this embodiment, the plastic-coated composite steel pipe welding device can deliver inert protective gas to the welding area through the nozzle 670, the air inlet pipe 680 and the gas compressor to avoid oxidation of the weld pool, solve the problem of reduced joint strength caused by welding oxidation, and improve the corrosion resistance and anti-aging performance of the welded joint.

[0037] 4. In this embodiment, the plastic-coated composite steel pipe welding device uses the high-precision characteristics of screw drive to drive the welding torch 420 and welding rod 430 to move precisely in the horizontal direction, adapting to the welding interface position of steel pipes of different lengths and diameters. With the help of the adjustment mechanism, the mounting plate 650 is driven to adjust the angle in the vertical direction, realizing welding from multiple angles such as flat welding and vertical welding of the welding torch 420. This solves the problem of "fixed angle and poor adaptability" of traditional devices, expands the application range of the device, avoids the errors that occur in manual welding, and thus improves the welding effect of steel pipes.

[0038] In summary, the above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be covered by the present invention.

Claims

1. A welding device for plastic-coated composite steel pipes, characterized in that: The device includes a welding apparatus body (100), which includes a mounting base (110). The mounting base (110) has a welding cavity (210) for placing the steel pipe to be welded. The mounting base (110) has a sealing cover (120) for sealing the welding cavity (210). The welding cavity (210) has at least four sets of clamping mechanisms for clamping the steel pipe to be welded. The welding cavity (210) has a welding mechanism for welding the steel pipe to be welded. The outer wall of the mounting base (110) has a connector (130) communicating with the welding cavity (210). The connector (130) is connected to an exhaust pipe (140), which is used to connect to a vacuum pump to extract the gas in the welding cavity (210).

2. The welding device for plastic-coated composite steel pipes according to claim 1, characterized in that: The clamping mechanism includes at least two first hydraulic push rods (220) disposed at the bottom wall of the welding cavity (210) and at least two first hydraulic push rods (120) disposed at the sealing cover (120), and clamping rollers (230) are rotatably disposed at the end of the piston rod of the first hydraulic push rods (220).

3. The welding device for plastic-coated composite steel pipes according to claim 2, characterized in that: At the center of the bottom end face of the welding cavity (210), there is a drive mechanism for cooperating with the clamping mechanism to rotate the steel pipe to be welded. The drive mechanism includes a second hydraulic push rod (240). The end of the piston rod of the second hydraulic push rod (240) is provided with a roller mounting bracket (250). A driven wheel (310) is rotatably provided at the roller mounting bracket (250). A drive motor (320) for driving the driven wheel (310) to rotate is provided at the roller mounting bracket (250). A first pulley (330) is provided at the shaft of the drive motor (320). The axle of the driven wheel (310) extends out of the roller mounting bracket (250). A second pulley (340) is provided at the end of the driven wheel (310) extending out of the roller mounting bracket (250). A transmission belt (350) is provided between the first pulley (330) and the second pulley (340).

4. The welding device for plastic-coated composite steel pipes according to claim 1, characterized in that: The welding mechanism includes two sets of lead screw (610) drive mechanisms, which are located at the sealing cover (120) and arranged opposite to each other. Each set of lead screw (610) drive mechanisms includes a base plate (410), which is bolted to the side wall of the sealing cover (120). A slide rail (510) is provided at the base plate (410), and a sliding plate (520) is slidably provided above the slide rail (510). A slider (530) that cooperates with the slide rail (510) is provided at the bottom end face of the sliding plate (520). A lead screw (610) is provided at the bottom of the sliding plate (520) and a lead screw nut (620) is provided at the bottom end of the sliding plate (520) to cooperate with the lead screw (610). A lead screw motor (540) for driving the lead screw (610) to rotate is also provided at the bottom plate (410). A welding gun (420) is provided at the sliding plate (520) of one of the two sets of lead screw (610) driving mechanisms, and a welding rod (430) is provided at the sliding plate (520) of the other set of lead screw (610) driving mechanism.

5. The welding device for plastic-coated composite steel pipes according to claim 4, characterized in that: The sliding plate (520) is provided with an adjustment mechanism for adjusting the vertical angle of the welding torch (420) and the welding rod (430). The adjustment mechanism includes two vertical plates (630), which are located at the sliding plate (520) and arranged opposite to each other. A rotating column (640) is rotatably provided between the two vertical plates (630). A mounting plate (650) for placing the welding torch (420) and the welding rod (430) is fixedly connected to the rotating column (640). One of the two vertical plates (630) is provided with an adjustment motor (660) for driving the rotating column (640) to rotate.

6. The welding device for plastic-coated composite steel pipes according to claim 5, characterized in that: The welding torch (420) is mounted on a mounting plate (650) with a nozzle (670) connected to the nozzle (670). The end of the air inlet pipe (680) passes through the sealing cover (120) and extends out of the welding chamber (210). The end of the air inlet pipe (680) extending out of the welding chamber (210) is connected to a gas compressor.

7. The welding device for plastic-coated composite steel pipes according to claim 5, characterized in that: The upper end of the mounting plate (650) is bolted to the upper cover plate (710). The adjacent end faces of the mounting plate (650) and the upper cover plate (710) are provided with arc-shaped grooves (720). The arc-shaped grooves (720) on the mounting plate (650) and the arc-shaped grooves (720) on the upper cover plate (710) together form a mounting groove (730) for mounting a welding gun (420), welding rod (430), or nozzle (670).

8. The welding device for plastic-coated composite steel pipes according to claim 2, characterized in that: The clamping roller (230) is made of rubber.

9. The welding device for plastic-coated composite steel pipes according to claim 1, characterized in that: One end of the sealing cover (120) is hinged to the mounting base (110), and the other end of the sealing cover (120) expands outward to form a sealing cover protrusion (121). The mounting base (110) is provided with a mounting base protrusion (111) corresponding to the sealing cover protrusion (121), and the sealing cover protrusion (121) and the mounting base protrusion (111) are bolted together.

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