Welding device for large-diameter plastic-coated steel pipe

Abstract

The invention belongs to the technical field of steel pipe welding, and particularly relates to a welding device for a large-diameter plastic-coated steel pipe, the welding device comprises a base, a support, a first air cylinder and a welding gun, the support is fixedly arranged at the top of the base, the first air cylinder is arranged on the support, the welding gun is fixedly arranged at the moving end of the first air cylinder, and the first air cylinder is arranged on the support. The two clamping mechanisms are arranged between the two sides of the top of the base and the two sides of the top of the support correspondingly, and the two clamping mechanisms can clamp and fix the two large-diameter plastic-coated steel pipes which are in butt joint; and the transverse moving mechanism is arranged at the top of the bracket. The PLC is used for controlling and coordinating actions of all the mechanisms, it is guaranteed that welding, cooling and smoke removal are conducted synchronously, the welding efficiency and the quality stability are improved, the problems that an existing welding device is insufficient in heat input regulation and control, a coating is prone to damage, and the working environment is poor are solved, and the corrosion resistance and the service life of the large-diameter plastic-coated steel pipe are guaranteed.

Description

Technical Field

[0001] The present invention belongs to the technical field of steel pipe welding, and in particular relates to a welding device for large-diameter plastic-coated steel pipes. Background Art

[0002] Due to the combination of the mechanical properties of steel and the anti-corrosion characteristics of plastic, large-diameter plastic-coated steel pipes are widely used in infrastructure fields such as water conservancy and municipal engineering. Since the single length of large-diameter plastic-coated steel pipes is usually 6-12 meters, while actual projects (such as municipal pipe networks and long-distance pipelines) require continuous pipe systems of hundreds of meters to dozens of kilometers, therefore, it is necessary to connect segmented large-diameter plastic-coated steel pipes into a whole by welding. For example, a new plastic-coated steel pipe manufacturing device for manufacturing large-diameter anti-corrosion plastic-coated steel pipes disclosed in the publication number CN220073799U.

[0003] However, the existing welding devices can only complete the process of fusion welding into one body, without integrating a cooling module, and cannot effectively regulate the welding heat input. The thickness of the plastic coating is usually 0.3-1.5 mm, and its heat resistance limit is relatively low (the softening point of polyethylene is about 120 °C, and the short-term heat resistance of epoxy resin ≤ 180 °C). The heat input of conventional welding devices is large, and the width of the heat-affected zone of the weld can reach 100-150 mm, resulting in carbonization, bulging and delamination of the coating at high temperatures. After the plastic coating of large-diameter plastic-coated steel pipes is damaged, the metal substrate will corrode at an accelerated rate under special geological conditions such as collapsible loess and saline soil, thus affecting the service life of large-diameter plastic-coated steel pipes.

[0004] Therefore, a welding device for large-diameter plastic-coated steel pipes is proposed. Summary of the Invention

[0005] The object of the present invention is to solve the above problems and provide a welding device for large-diameter plastic-coated steel pipes.

[0006] To achieve the above object, the present invention adopts the following technical solutions: A welding device for large-diameter plastic-coated steel pipes includes a base, a bracket, a first cylinder and a welding torch. The bracket is fixedly arranged on the top of the base, the first cylinder is arranged on the bracket, and the welding torch is fixedly arranged on the moving end of the first cylinder. It further includes: Two clamping mechanisms are respectively arranged between the two sides of the top of the base and the two sides of the top of the bracket. The two clamping mechanisms can clamp and fix the two butt-jointed large-diameter plastic-coated steel pipes. A transverse moving mechanism is arranged on the top of the bracket. Two suspension rods are symmetrically and fixedly arranged at the bottom of the transverse moving mechanism. The same suspension ring is fixedly arranged at the lower ends of the two suspension rods. The rotating mechanism is arranged on the sling. The first cylinder is fixedly arranged on the inner side wall of the rotating mechanism. Two support rods are symmetrically and fixedly arranged on the cylinder wall of the first cylinder. The upper ends of the two support rods are respectively fixedly provided with a first support plate and a second support plate; The cooling mechanism is arranged between the side wall of the first cylinder, the first support plate and the second support plate, and the cooling mechanism is located on both sides of the welding torch. The cooling mechanism is used to cool the two side surfaces of the welding part of the large-diameter plastic-coated steel pipe; The smoke removal mechanism is fixedly arranged on the lower surface of the second support plate, and the detection end of the smoke removal mechanism extends to one side of the welding torch; The blowing mechanism is arranged on the side wall of the smoke removal mechanism, and the blowing end of the blowing mechanism extends to the welds of the two large-diameter plastic-coated steel pipes; The PLC controller is fixedly arranged on the side wall of the bracket. The first cylinder, the welding torch, the clamping mechanism, the transverse moving mechanism, the rotating mechanism, the cooling mechanism, the smoke removal mechanism and the blowing mechanism are all electrically connected to the PLC controller.

[0007] Preferably, the clamping mechanism includes an arc-shaped support seat fixedly arranged on the top of the base, and a second cylinder is fixedly arranged on the top of the bracket. The moving end of the second cylinder is fixedly provided with an arc-shaped pressing plate.

[0008] Preferably, the transverse moving mechanism includes two X-axis electric slide rails symmetrically and fixedly arranged on the top of the bracket. A slider is arranged between the two X-axis electric slide rails. The bottom of the slider is fixedly connected to the upper ends of the two suspension rods.

[0009] Preferably, the rotating mechanism includes a motor fixedly arranged on the top of the sling. A gear is fixedly arranged on the output shaft of the motor. The sling is of a hollow structure, and a gear ring is rotatably arranged inside the sling through a bearing. The gear ring is meshed with the gear, and the tail of the first cylinder is fixedly arranged on the top inner wall of the gear ring.

[0010] Preferably, the cooling mechanism includes a water supply tank fixedly arranged on the lower surface of the first support plate and a water return tank fixedly arranged on the lower surface of the second support plate. The moving end of the first cylinder is symmetrically provided with a first arc-shaped cooling plate and a second arc-shaped cooling plate. Both the first arc-shaped cooling plate and the second arc-shaped cooling plate are of a hollow structure. A water supply pipe is fixedly arranged on the top of the first arc-shaped cooling plate, and the upper end of the water supply pipe is connected to the water supply pump inside the water supply tank. An electromagnetic flow valve is arranged on the pipe wall of the water supply pipe. A water return pipe is fixedly arranged on the top of the second arc-shaped cooling plate, and the upper end of the water return pipe is fixedly connected to the side wall of the water return tank. A connecting pipe is fixedly arranged between the first arc-shaped cooling plate and the second arc-shaped cooling plate.

[0011] Preferably, two fixing blocks are symmetrically and fixedly arranged at the moving end of the first cylinder. Two sliding rods are symmetrically arranged on each of the two fixing blocks. The lower ends of the sliding rods on the same side are respectively fixedly connected to the first arc-shaped cooling plate and the second arc-shaped cooling plate, and springs are fixedly arranged between the upper ends of the sliding rods on the same side and the fixing blocks.

[0012] Preferably, a cleaning brush is fixedly arranged on one side of the first arc-shaped cooling plate. The cleaning brush is located on one side of the first arc-shaped cooling plate and the second arc-shaped cooling plate and is close to the space between the first arc-shaped cooling plate and the second arc-shaped cooling plate.

[0013] Preferably, the smoke removal mechanism includes an air suction cylinder fixedly arranged on the lower surface of the second support plate. An air suction fan is fixedly arranged inside the air suction cylinder. Multiple layers of filter nets are fixedly arranged inside the air suction cylinder and above the air suction fan. An air suction pipe is fixedly arranged at the bottom of the air suction cylinder, and the end of the air suction pipe extends to one side of the welding torch. A fixing sleeve is threadedly arranged at the end of the air suction pipe, and a temperature sensor is fixedly arranged inside the fixing sleeve.

[0014] Preferably, the air blowing mechanism includes an air blowing pipe fixedly arranged on the side wall of the air suction cylinder. The end of the air blowing pipe extends to one side of the first arc-shaped cooling plate and the second arc-shaped cooling plate and is fixedly provided with a hollow air blowing plate. A plurality of uniformly distributed air blowing holes are formed on the lower surface of the hollow air blowing plate, and a cooler is arranged on the pipe wall of the air blowing pipe.

[0015] Compared with the existing technology, the beneficial effects of the present invention are as follows: 1. By setting the rotation mechanism and the cooling mechanism, the rotation mechanism drives the gear to engage with the gear ring through the motor, so that the welding torch rotates 360° around the axis of the large-diameter plastic-coated steel pipe to complete the continuous welding of the circumferential weld. At the same time, the cooling mechanism can cool the two sides of the welding part, quickly reduce the temperature of the two sides of the weld to the coating safety threshold, effectively avoid defects such as carbonization and bulging of the plastic coating. Moreover, the cooling mechanism can also move synchronously in a circular manner to realize the coordinated operation of full circumferential welding and dynamic cooling, improving the welding efficiency and quality.

[0016] 2. By setting the smoke removal mechanism, the air suction fan sucks the welding smoke into the air suction cylinder through the air suction pipe. At the same time, the smoke passes through multiple layers of filter nets and is purified by three levels: the primary fiberglass mesh, the activated carbon adsorption layer, and the HEPA high-efficiency filter layer, effectively removing harmful substances such as welding slag particles and VOCs, improving the working environment. At the same time, a temperature sensor is arranged at the end of the air suction pipe, and the temperature sensor can detect the temperature of the smoke gas and dynamically and accurately adjust the opening degree of the electromagnetic flow valve according to the temperature value, so as to realize the intelligent control of the cooling water volume.

[0017] 3. Through the provided air-blowing mechanism, the high-temperature gas purified by the smoke-removing mechanism is cooled to room temperature by the cooler and then blows on the weld through the uniform air-blowing holes of the hollow air-blowing plate. While avoiding sudden cooling damage to the coating, it accelerates the cooling of the weld, achieving the dual effects of smoke purification and weld cooling, and enhancing the environmental protection and safety of the welding process. Description of the Drawings

[0018] Figure 1 is a perspective view of the first angle of a welding device for large-diameter plastic-coated steel pipes provided by the present invention; Figure 2 is a perspective view of the second angle of a welding device for large-diameter plastic-coated steel pipes provided by the present invention; Figure 3 is a perspective view of the connection of the lateral movement mechanism, suspension rod and suspension ring of a welding device for large-diameter plastic-coated steel pipes provided by the present invention; Figure 4 is a perspective view of one side of the suspension ring of a welding device for large-diameter plastic-coated steel pipes provided by the present invention; Figure 5 is a perspective view of the other side of the suspension ring of a welding device for large-diameter plastic-coated steel pipes provided by the present invention; Figure 6 is a perspective view of the sectioned suspension ring of a welding device for large-diameter plastic-coated steel pipes provided by the present invention; Figure 7 is a perspective view of the structures on both sides of the first cylinder and the welding torch of a welding device for large-diameter plastic-coated steel pipes provided by the present invention; Figure 8 is a perspective view of the smoke-removing mechanism and the air-blowing mechanism of a welding device for large-diameter plastic-coated steel pipes provided by the present invention; Figure 9 is a partial perspective view of the end face of the suction air pipe of a welding device for large-diameter plastic-coated steel pipes provided by the present invention.

[0019] In the figure: 1 base, 2 support, 3 first cylinder, 4 welding torch, 5 clamping mechanism, 51 arc-shaped support, 52 second cylinder, 53 arc-shaped pressing plate, 6 transverse movement mechanism, 61 X-axis electric slide rail, 62 slider, 7 suspension rod, 8 lifting ring, 9 rotation mechanism, 91 motor, 92 gear, 93 gear ring, 10 support rod, 11 first support plate, 12 second support plate, 13 cooling mechanism, 131 water supply tank, 132 water return tank, 133 first arc-shaped cooling plate, 134 second arc-shaped cooling plate, 135 water supply pipe, 136 electromagnetic flow valve, 137 water return pipe, 138 connecting pipe, 14 fume removal mechanism, 141 air suction cylinder, 142 air suction fan, 143 multi-layer filter screen, 144 air suction pipe, 145 fixed sleeve, 146 temperature sensor, 15 blowing mechanism, 151 blowing pipe, 152 hollow blowing plate, 153 blowing hole, 154 cooler, 16 PLC controller, 17 fixed block, 18 sliding rod, 19 spring, 20 cleaning brush. Detailed implementation manners

[0020] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0021] As Figures 1-9 shown, a welding device for large-diameter plastic-coated steel pipes includes a base 1, a support 2, a first cylinder 3 and a welding torch 4. The support 2 is fixedly arranged on the top of the base 1. The first cylinder 3 is arranged on the support 2. The welding torch 4 is fixedly arranged on the moving end of the first cylinder 3. It further includes: Two clamping mechanisms 5 are respectively arranged between the two sides of the top of the base 1 and the two sides of the top of the support 2. The two clamping mechanisms 5 can clamp and fix the two butt-jointed large-diameter plastic-coated steel pipes. The clamping mechanism 5 includes an arc-shaped support 51 fixedly arranged on the top of the base 1. A second cylinder 52 is fixedly arranged on the top of the support 2. The moving end of the second cylinder 52 is fixedly provided with an arc-shaped pressing plate 53. The two large-diameter plastic-coated steel pipes to be welded are smoothly placed into the inside of the two arc-shaped supports 51. Control the second cylinder 52 to start extending, drive the corresponding arc-shaped pressing plate 53 to move down smoothly. The inner surface of the arc-shaped pressing plate 53 perfectly fits the top contour of the large-diameter plastic-coated steel pipe and completes stable clamping.

[0022] The horizontal movement mechanism 6 is arranged at the top of the bracket 2. Two suspension rods 7 are symmetrically and fixedly arranged at the bottom of the horizontal movement mechanism 6. The same suspension ring 8 is fixedly arranged at the lower ends of the two suspension rods 7. The horizontal movement mechanism 6 includes two X-axis electric slide rails 61 symmetrically and fixedly arranged at the top of the bracket 2. A slider 62 is arranged between the two X-axis electric slide rails 61. The bottom of the slider 62 is fixedly connected to the upper ends of the two suspension rods 7. By starting the two X-axis electric slide rails 61, the slider 62 can slide smoothly along the horizontal track, driving the suspension rods 7 and the suspension ring 8 at the bottom of the slider 62 to move synchronously.

[0023] The rotation mechanism 9 is arranged on the suspension ring 8. The first cylinder 3 is fixedly arranged on the inner side wall of the rotation mechanism 9. The rotation mechanism 9 includes a motor 91 fixedly arranged on the top of the suspension ring 8. A gear 92 is fixedly arranged on the output shaft of the motor 91. The suspension ring 8 is of a hollow structure, and a gear ring 93 is rotatably arranged in the suspension ring 8 through a bearing. The gear ring 93 is meshed with the gear 92. The tail of the first cylinder 3 is fixedly arranged on the inner wall of the top of the gear ring 93. When the motor 91 operates, it can drive the gear 92 to rotate, and the gear 92 can drive the gear ring 93 to rotate, so that the gear ring 93 rotates inside the suspension ring 8. Since the first cylinder 3 is fixedly connected to the inner wall of the gear ring 93, the welding torch 4 can be driven to rotate 360° around the axis of the large-diameter plastic-coated steel pipe; two support rods 10 are symmetrically and fixedly arranged on the barrel wall of the first cylinder 3. The first support plate 11 and the second support plate 12 are respectively fixedly arranged at the upper ends of the two support rods 10.

[0024] The cooling mechanism 13 is arranged between the side wall of the first cylinder 3, the first support plate 11 and the second support plate 12, and the cooling mechanism 13 is located on both sides of the welding torch 4. The cooling mechanism 13 is used to cool the two side surfaces of the welding part of the large-diameter plastic-coated steel pipe. The cooling mechanism 13 includes a water supply tank 131 fixedly arranged on the lower surface of the first support plate 11 and a water return tank 132 fixedly arranged on the lower surface of the second support plate 12. The moving end of the first cylinder 3 is symmetrically provided with a first arc-shaped cooling plate 133 and a second arc-shaped cooling plate 134. The moving end of the first cylinder 3 is symmetrically and fixedly provided with two fixing blocks 17. Two sliding rods 18 are symmetrically slidably arranged on both fixing blocks 17. The lower ends of the sliding rods 18 on the same side are respectively fixedly connected to the first arc-shaped cooling plate 133 and the second arc-shaped cooling plate 134. A spring 19 is fixedly arranged between the upper ends of the sliding rods 18 on the same side and the fixing blocks 17. The first arc-shaped cooling plate 133 and the second arc-shaped cooling plate 134 can move up and down inside the fixing blocks 17 through the sliding rods 18, and the upper ends of the sliding rods 18 are provided with springs 19, which can enable the first arc-shaped cooling plate 133 and the second arc-shaped cooling plate 134 to have the function of elastic expansion and contraction; both the first arc-shaped cooling plate 133 and the second arc-shaped cooling plate 134 are of a hollow structure. A water supply pipe 135 is fixedly arranged at the top of the first arc-shaped cooling plate 133, and the upper end of the water supply pipe 135 is connected to the water supply pump inside the water supply tank 131. An electromagnetic flow valve 136 is arranged on the pipe wall of the water supply pipe 135. A water return pipe 137 is fixedly arranged at the top of the second arc-shaped cooling plate 134, and the upper end of the water return pipe 137 is fixedly connected to the side wall of the water return tank 132. A connecting pipe 138 is fixedly arranged between the first arc-shaped cooling plate 133 and the second arc-shaped cooling plate 134. When the water supply pump inside the water supply tank 131 operates (an elastic piston plate is arranged inside the water supply tank 131. During the 360° rotation of the water supply tank 131, in order to ensure continuous water supply to the water supply pump inside the water supply tank 131, the elastic piston plate can continuously press the cooling water into the position of the water supply pump. For example, when the water supply tank 131 rotates to the lowest position, at this time, the water supply pump may be located at the top position, and the cooling water flows downward due to gravity. The elastic piston plate is pushed by the elastic force to press the cooling water into the position of the water supply pump), the cooling water can be pumped into the water supply pipe 135, and is transported to the inside of the first arc-shaped cooling plate 133 through the water supply pipe 135. Since the first arc-shaped cooling plate 133 and the second arc-shaped cooling plate 134 are connected through the connecting pipe 138, the cooling water fills the internal flow channels of the first arc-shaped cooling plate 133 and the second arc-shaped cooling plate 134;On one side of the first arc-shaped cooling plate 133, a cleaning brush 20 is fixedly arranged. The cleaning brush 20 is located on one side of the first arc-shaped cooling plate 133 and the second arc-shaped cooling plate 134, and is close to the space between the first arc-shaped cooling plate 133 and the second arc-shaped cooling plate 134. During the rotation of the first arc-shaped cooling plate 133 and the second arc-shaped cooling plate 134, the cleaning brush 20 will be driven to rotate together. Since the cleaning brush 20 is aligned with the butt joint part of the large-diameter plastic-coated steel pipe, the cleaning brush 20 can clean the butt joint part of the large-diameter plastic-coated steel pipe to prevent impurities from adhering and affecting the welding quality.;

[0025] The smoke removal mechanism 14 is fixedly arranged on the lower surface of the second support plate 12, and the detection end of the smoke removal mechanism 14 extends to one side of the welding torch 4. The smoke removal mechanism 14 includes a suction cylinder 141 fixedly arranged on the lower surface of the second support plate 12. Inside the suction cylinder 141, a suction fan 142 is fixedly arranged. Inside the suction cylinder 141 and above the suction fan 142, multiple layers of filter nets 143 are fixedly arranged. At the bottom of the suction cylinder 141, a suction pipe 144 is fixedly arranged, and the end of the suction pipe 144 extends to one side of the welding torch 4. At the end of the suction pipe 144, a fixing sleeve 145 is threaded, and inside the fixing sleeve 145, a temperature sensor 146 is fixedly arranged. When the suction fan 142 operates, it quickly evacuates the air inside the suction cylinder 141 and the suction pipe 144, creating a negative pressure environment inside the suction pipe 144, so that the smoke and harmful gases generated during the welding process can be quickly sucked into the suction cylinder 141 and filtered through the multiple layers of filter nets 143 inside the suction cylinder 141. When the smoke gas is about to enter the suction pipe 144, it will first flow through the inside of the fixing sleeve 145. The temperature sensor 146 installed inside the fixing sleeve 145 can detect the temperature of the smoke gas.

[0026] The blowing mechanism 15 is arranged on the side wall of the smoke removal mechanism 14, and the blowing end of the blowing mechanism 15 extends to the weld of the two large-diameter plastic-coated steel pipes. The blowing mechanism 15 includes a blowing pipe 151 fixedly arranged on the side wall of the suction cylinder 141. The end of the blowing pipe 151 extends to one side of the first arc-shaped cooling plate 133 and the second arc-shaped cooling plate 134 and is fixedly provided with a hollow blowing plate 152. On the lower surface of the hollow blowing plate 152, a plurality of uniformly distributed blowing holes 153 are opened. A cooler 154 is arranged on the pipe wall of the blowing pipe 151. The purified gas flows through the inside of the blowing pipe 151. When passing through the inside of the blowing pipe 151, the high-temperature gas is quickly cooled to room temperature by the provided cooler 154. Subsequently, the room-temperature gas is introduced into the inside of the hollow blowing plate 152 and evenly blown to the weld area of the large-diameter plastic-coated steel pipe after welding through the multiple blowing holes 153 on the hollow blowing plate 152.

[0027] The PLC controller 16 is fixedly arranged on the side wall of the bracket 2, and the first cylinder 3, the welding torch 4, the clamping mechanism 5, the lateral moving mechanism 6, the rotating mechanism 9, the cooling mechanism 13, the smoke exhaust mechanism 14 and the blowing mechanism 15 are all electrically connected to the PLC controller 16.

[0028] The operation principle of the present invention is described as follows: Before welding large-diameter plastic-coated steel pipes, the staff operates the crane and slowly and steadily places the two large-diameter plastic-coated steel pipes to be welded into the inside of the two arc-shaped brackets 51 in sequence. During the hoisting and placing process, two other staff members assist in pushing the two large-diameter plastic-coated steel pipes by hand, so that the ends of the two large-diameter plastic-coated steel pipes pass through the inside of the suspension rings 8, and the positions are gradually adjusted until the ends of the two large-diameter plastic-coated steel pipes are in a butting state, preparing for the subsequent circumferential welding. After the two large-diameter plastic-coated steel pipes are completely placed in the arc-shaped brackets 51, the staff operates the PLC controller 16 to send instructions to the two second cylinders 52. The two second cylinders 52 that receive the instructions start to extend, driving the corresponding arc-shaped pressing plates 53 to move downward steadily. The inner surface of the arc-shaped pressing plate 53 perfectly fits the top contour of the large-diameter plastic-coated steel pipe. As the second cylinder 52 continues to push out, the two arc-shaped pressing plates 53 are respectively tightly attached to the tops of the two large-diameter plastic-coated steel pipes, applying pressure from above and forming an up-and-down clamping force with the arc-shaped brackets 51 below, completing the stable and reliable clamping and fixing of the large-diameter plastic-coated steel pipes, preventing displacement, shaking and other situations during the subsequent welding process, and ensuring the smooth progress of the subsequent welding work; After completing the clamping and fixing of the large-diameter plastic-coated steel pipes, the staff again issued instructions to the equipment through the PLC controller 16, and started the two X-axis electric slides 61 and the first cylinder 3 in order. As the X-axis electric slide 61 started to operate, the slider 62 slid smoothly along the horizontal track, driving the suspension rod 7 and the suspension ring 8 at the bottom of the slider 62 to move synchronously. Then, the first cylinder 3 received the instruction, and the internal piston rod was quickly extended, pushing the welding gun 4 at the lower end to slowly move downward in the vertical direction and approach the docking position of the two large-diameter plastic-coated steel pipes. In the process of the welding gun 4 descending, the first arc cooling plate 133 and the second arc cooling plate 134 arranged on both sides of the first cylinder 3 also descended synchronously, and the first arc cooling plate 133 and the second arc cooling plate 134 were aligned with the outer walls of the two large-diameter plastic-coated steel pipes. Fitting, when the first arc cooling plate 133 and the second arc cooling plate 134 are in contact with the surface of the large-diameter plastic-coated steel pipe, the reaction force of the large-diameter plastic-coated steel pipe will push the sliding rod 18 connected thereto upward, and the upward movement of the sliding rod 18 stretches the spring 19 installed on its upper end, and the elastic restoring force of the spring 19 presses the first arc cooling plate 133 and the second arc cooling plate 134 onto the surface of the large-diameter plastic-coated steel pipe, giving the first arc cooling plate 133 and the second arc cooling plate 134 the characteristic of elastic expansion and contraction, which can ensure that the first arc cooling plate 133 and the second arc cooling plate 134 are tightly fitted with the large-diameter plastic-coated steel pipe, and avoid damage to the plastic coating layer due to excessive contact force, thus making full preparations for subsequent cooling work and enabling the welding gun 4 to be accurately aligned with the butt joint of the two large-diameter plastic-coated steel pipes; After the welding gun 4 is precisely aligned, the staff starts the welding gun 4, the water supply pump inside the water supply tank 131 and the motor 91 synchronously through the PLC controller 16, triggering the welding and cooling collaborative operation process. The welding gun 4 adopts the melting electrode gas shielded welding process, and the continuous solid welding wire is fed into the welding area through the wire feeding mechanism. When the welding wire contacts the butt joint of the large-diameter plastic-coated steel pipe, an arc is formed between the end of the welding wire and the butt joint under the action of the high current provided by the welding power supply. The high temperature of the arc causes the welding wire and the butt joint to melt rapidly, realizing the metallurgical bonding of the two large-diameter plastic-coated steel pipes. At the same time, the water supply pump inside the water supply tank 131 draws cooling water into the water supply tank 131. The water pipe 135 is transported to the inside of the first curved cooling plate 133 through the water supply pipe 135. Since the first curved cooling plate 133 and the second curved cooling plate 134 are connected through the connecting pipe 138, the cooling water is evenly filled in the internal flow channels of the first curved cooling plate 133 and the second curved cooling plate 134 under pressure. The first curved cooling plate 133 and the second curved cooling plate 134 are made of high thermal conductivity aluminum alloy substrates, and the curved inner wall thereof is precisely fitted with the outer wall of the large-diameter plastic-coated steel pipe, which can quickly take away the heat from the welding area. After absorbing the heat, the cooling water increases in temperature and is discharged into the return water tank 132 through the return water pipe 137, forming a closed-loop circulation cooling system; When the motor 91 runs, it can drive the gear 92 to rotate. The gear 92 meshes with the internal gear ring 93 of the lifting ring 8, causing the gear ring 93 to rotate inside the lifting ring 8. Since the first cylinder 3 is fixedly connected to the inner wall of the gear ring 93, it can drive the welding torch 4 to rotate 360° around the axis of the large-diameter plastic-coated steel pipe. During this process, the welding torch 4 moves uniformly along the butt circumferential weld of the large-diameter plastic-coated steel pipe, forming a continuous and uniform circumferential weld. The first arc-shaped cooling plate 133 and the second arc-shaped cooling plate 134 on both sides rotate synchronously with the first cylinder 3, always keeping in contact with the two side surfaces of the welding area of the large-diameter plastic-coated steel pipe, forming dynamic tracking cooling. Since the surfaces of the first arc-shaped cooling plate 133 and the second arc-shaped cooling plate 134 are both provided with a PTFE coating with a low coefficient of friction (coefficient of friction < 0.1) and are elastically loaded through elastic connection, the first arc-shaped cooling plate 133 and the second arc-shaped cooling plate 134 can ensure good cooling effect during the sliding process and avoid scratching the surface plastic coating of the large-diameter plastic-coated steel pipe. This design controls the width of the heat-affected zone within 50 mm (the traditional process is 100 - 150 mm), quickly reduces the temperature on both sides of the weld to below the coating safety threshold (< 180 °C), effectively avoiding defects such as carbonization and bulging of the plastic coating. The entire welding process precisely synchronizes the actions of each actuator by the PLC controller 16. The welding speed is stable at 300 - 500 mm / min, and the circumferential weld is formed in one pass, significantly improving the welding quality and production efficiency of the large-diameter plastic-coated steel pipe; During the continuous welding operation, the staff starts the suction fan 142 through the PLC controller 16. The suction fan 142 quickly evacuates the air in the suction air cylinder 141 and the suction air pipe 144 with strong suction force, creating a negative pressure environment inside the suction air pipe 144. Since the port of the suction air pipe 144 is arranged on one side of the welding torch 4, the smoke and harmful gases generated during the welding process are quickly sucked into the suction air cylinder 141 and filtered through the multi-layer filter screen 143 inside the suction air cylinder 141. The first layer of the multi-layer filter screen 143 is the primary filter layer, which uses a glass fiber mesh with an increasing density gradient and can intercept welding slag particles and metal oxides with a particle size greater than 5 microns; the middle layer is the activated carbon adsorption layer, which is made of high-iodine-value coconut shell activated carbon. Its developed pore structure and large specific surface area can efficiently adsorb volatile organic compounds (VOCs) such as formaldehyde and styrene and acidic gases in the welding smoke. The innermost layer is the HEPA high-efficiency filter layer, which is made of ultra-fine glass fiber filter paper treated by electrostatic electret technology and can capture fine particles above 0.3 microns. Through the coordinated action of these three filter screens, the harmful substances in the smoke are intercepted layer by layer, and the purified gas enters the subsequent treatment process; The purified gas flows through the interior of the blowing pipe 151, and then passes through the interior of the blowing pipe 151 again. Through the provided cooler 154, the cooler 154, based on the compression refrigeration principle, rapidly cools the high-temperature gas to room temperature. Subsequently, the room-temperature gas is introduced into the interior of the hollow blowing plate 152 and is evenly blown through multiple blowing holes 153 on the hollow blowing plate 152 onto the weld area after the large-diameter plastic-coated steel pipe is welded. This design not only realizes the harmless treatment of welding fumes but also cleverly utilizes the gas for weld cooling. While ensuring the cleanliness of the working environment, it accelerates the cooling of the weld, comprehensively improving the welding quality and operation safety (the room-temperature gas can effectively take away the residual heat of the weld and avoid damage to the coating caused by sudden cooling, meeting the requirements of cooling and coating protection); During the synchronous operation of welding, cooling, and fume removal, when the fume gas is about to enter the suction pipe 144, it will first flow through the interior of the fixed sleeve 145. A temperature sensor 146 is installed inside the fixed sleeve 145, which can detect the temperature of the fume gas and quickly feedback the detected temperature value to the PLC controller 16. After receiving the temperature value, the PLC controller 16 will immediately activate the pre-set intelligent control algorithm inside. This algorithm will dynamically and precisely adjust the opening degree of the electromagnetic flow valve 136 according to the feedback temperature value, thereby realizing the intelligent control of the cooling water volume. When the temperature of the fume gas generated during the welding process is relatively high, it indicates that the temperature of the current welding area is relatively high. At this time, the temperature value detected by the temperature sensor 146 is relatively large, and the PLC controller 16 will correspondingly increase the opening degree of the electromagnetic flow valve 136 based on this. As the opening degree of the electromagnetic flow valve 136 increases, more cooling water will quickly enter the interiors of the first arc-shaped cooling plate 133 and the second arc-shaped cooling plate 134. The increase in the cooling water flow significantly improves the heat exchange efficiency of the first arc-shaped cooling plate 133 and the second arc-shaped cooling plate 134, so that a large amount of heat generated in the welding area can be taken away more efficiently, effectively reducing the temperature of the welding part and suppressing the further expansion of the heat-affected zone, providing reliable protection for the plastic-coated layer. On the contrary, when the temperature of the fume gas is relatively low, it means that the welding temperature is relatively low. At this time, the temperature value detected by the temperature sensor 146 is relatively small, and the PLC controller 16 will correspondingly reduce the opening degree of the electromagnetic flow valve 136, controlling the appropriate reduction of the cooling water volume entering the interiors of the first arc-shaped cooling plate 133 and the second arc-shaped cooling plate 134 and reducing the heat exchange efficiency. This dynamic adjustment mechanism not only ensures the cooling effect during high-temperature welding but also avoids possible negative impacts caused by excessive cooling during low-temperature welding, such as problems like coating shrinkage and cracking. At the same time, it also has an adaptive adjustment ability, which can quickly respond and adjust the cooling water volume according to the real-time change of the temperature during the welding process, saving water resources to the greatest extent; After the welding is completed and the cooling is over, the staff operates the PLC controller 16 to release the fixation of the large-diameter plastic-coated steel pipe. Then, the welded large-diameter plastic-coated steel pipe is placed at the predetermined position by operating the crane, making full preparations for subsequent construction links such as the laying and connection of the large-diameter plastic-coated steel pipe.

[0029] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A welding device for large-diameter plastic-coated steel pipes, comprising a base (1), a bracket (2), a first cylinder (3) and a welding torch (4). The bracket (2) is fixedly arranged on the top of the base (1). The first cylinder (3) is arranged on the bracket (2). The welding torch (4) is fixedly arranged on the moving end of the first cylinder (3), characterized in that, It further includes: Two clamping mechanisms (5), respectively arranged between the two sides of the top of the base (1) and the two sides of the top of the bracket (2). The two clamping mechanisms (5) can clamp and fix the two large-diameter plastic-coated steel pipes after docking; A lateral movement mechanism (6), arranged on the top of the bracket (2). Two suspension rods (7) are symmetrically and fixedly arranged at the bottom of the lateral movement mechanism (6). The lower ends of the two suspension rods (7) are fixedly provided with the same suspension ring (8); A rotation mechanism (9), arranged on the suspension ring (8). The first cylinder (3) is fixedly arranged on the inner side wall of the rotation mechanism (9). Two support rods (10) are symmetrically and fixedly arranged on the cylinder wall of the first cylinder (3). The upper ends of the two support rods (10) are respectively fixedly provided with a first support plate (11) and a second support plate (12); A cooling mechanism (13), arranged between the side wall of the first cylinder (3), the first support plate (11) and the second support plate (12), and the cooling mechanism (13) is located on both sides of the welding torch (4). The cooling mechanism (13) is used to cool the two side surfaces of the welding part of the large-diameter plastic-coated steel pipe; A fume removal mechanism (14), fixedly arranged on the lower surface of the second support plate (12), and the detection end of the fume removal mechanism (14) extends to one side of the welding torch (4); A blowing mechanism (15), arranged on the side wall of the fume removal mechanism (14), and the blowing end of the blowing mechanism (15) extends to the weld of the two large-diameter plastic-coated steel pipes; A PLC controller (16), fixedly arranged on the side wall of the bracket (2). The first cylinder (3), the welding torch (4), the clamping mechanism (5), the lateral movement mechanism (6), the rotation mechanism (9), the cooling mechanism (13), the fume removal mechanism (14) and the blowing mechanism (15) are all electrically connected to the PLC controller (16).

2. The welding device for large-diameter plastic-coated steel pipes according to claim 1, wherein The clamping mechanism (5) includes an arc-shaped support seat (51) fixedly arranged on the top of the base (1). A second cylinder (52) is fixedly arranged on the top of the bracket (2). The moving end of the second cylinder (52) is fixedly provided with an arc-shaped pressing plate (53).

3. A welding device for large-diameter plastic-coated steel pipes according to claim 1, characterized in that, The lateral movement mechanism (6) includes two X-axis electric slide rails (61) symmetrically and fixedly arranged on the top of the bracket (2). A slider (62) is arranged between the two X-axis electric slide rails (61). The bottom of the slider (62) is fixedly connected to the upper ends of the two suspension rods (7).

4. A welding device for large-diameter plastic-coated steel pipes according to claim 1, characterized in that, The rotation mechanism (9) includes a motor (91) fixedly arranged on the top of the suspension ring (8). The output shaft of the motor (91) is fixedly provided with a gear (92). The suspension ring (8) is of a hollow structure, and a gear ring (93) is rotatably arranged inside the suspension ring (8) through a bearing. The gear ring (93) is meshed with the gear (92), and the tail of the first cylinder (3) is fixedly arranged on the inner wall of the top of the gear ring (93).

5. A welding device for large-diameter plastic-coated steel pipes according to claim 1, characterized in that, The cooling mechanism (13) includes a water supply tank (131) fixedly arranged on the lower surface of the first support plate (11) and a water return tank (132) fixedly arranged on the lower surface of the second support plate (12). Symmetrically arranged on the moving end of the first cylinder (3) are a first arc-shaped cooling plate (133) and a second arc-shaped cooling plate (134). Both the first arc-shaped cooling plate (133) and the second arc-shaped cooling plate (134) are of a hollow structure. A water supply pipe (135) is fixedly arranged at the top of the first arc-shaped cooling plate (133), and the upper end of the water supply pipe (135) is connected to a water supply pump inside the water supply tank (131). An electromagnetic flow valve (136) is arranged on the pipe wall of the water supply pipe (135). A water return pipe (137) is fixedly arranged at the top of the second arc-shaped cooling plate (134), and the upper end of the water return pipe (137) is fixedly connected to the side wall of the water return tank (132). A connecting pipe (138) is fixedly arranged between the first arc-shaped cooling plate (133) and the second arc-shaped cooling plate (134).

6. A welding device for large-diameter plastic-coated steel pipes according to claim 5, characterized in that, Symmetrically and fixedly arranged on the moving end of the first cylinder (3) are two fixed blocks (17). Symmetrically slidably arranged on each of the two fixed blocks (17) are two sliding rods (18). The lower ends of the sliding rods (18) on the same side are respectively fixedly connected to the first arc-shaped cooling plate (133) and the second arc-shaped cooling plate (134). A spring (19) is fixedly arranged between the upper end of the sliding rods (18) on the same side and the fixed block (17).

7. A welding device for large-diameter plastic-coated steel pipes according to claim 5, characterized in that, A cleaning brush (20) is fixedly arranged on one side of the first arc-shaped cooling plate (133). The cleaning brush (20) is located on one side of the first arc-shaped cooling plate (133) and the second arc-shaped cooling plate (134), and is close to the space between the first arc-shaped cooling plate (133) and the second arc-shaped cooling plate (134).

8. A welding device for large-diameter plastic-coated steel pipes according to claim 5, characterized in that, The smoke removal mechanism (14) includes an air suction cylinder (141) fixedly arranged on the lower surface of the second support plate (12). An air suction fan (142) is fixedly arranged inside the air suction cylinder (141). Multiple layers of filter meshes (143) are fixedly arranged inside the air suction cylinder (141) and above the air suction fan (142). An air suction pipe (144) is fixedly arranged at the bottom of the air suction cylinder (141), and the end of the air suction pipe (144) extends to one side of the welding torch (4). A fixing sleeve (145) is threaded on the end of the air suction pipe (144), and a temperature sensor (146) is fixedly arranged inside the fixing sleeve (145).

9. The welding device for large-diameter plastic-coated steel pipes according to claim 8, wherein, The air blowing mechanism (15) includes a blowing pipe (151) fixedly arranged on the side wall of the air suction cylinder (141). The end of the blowing pipe (151) extends to one side of the first arc-shaped cooling plate (133) and the second arc-shaped cooling plate (134) and is fixedly provided with a hollow air blowing plate (152). A plurality of uniformly distributed air blowing holes (153) are formed on the lower surface of the hollow air blowing plate (152). A cooler (154) is arranged on the pipe wall of the blowing pipe (151).

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