A low stress welded joint process for wind power pipe pile structures

Abstract

The present application relates to the wind power generation pipe pile manufacturing technical field, specifically relates to a kind of low stress welding joint process for wind power pipe pile structure, for welding stud or support to the barrel wall of tower pipe pile, including polishing welding area, positioning welding, fillet welding, weld cleaning, weld toe self-fusion treatment and other steps.The joint formed by the present application using flux-cored wire arc welding (FCAW)+self-fusion tungsten inert gas welding (TIG) welding method not only improves production efficiency, reduces production cost, but also guarantees the high quality and high strength of weld, provides strong guarantee for the fatigue and safety and reliability of engineering.Through weld toe self-fusion instead of traditional post-welding polishing treatment, avoid base metal damage and repeated repair welding, simplify process, shorten construction period, significantly improve the production efficiency and economy of wind power pipe pile inner wall accessory welding.

Description

Technical Field

[0001] This invention relates to the field of wind power pipe pile manufacturing technology, and specifically to a low-stress welding joint process for wind power pipe pile structures. Background Technology

[0002] Offshore wind turbine piles are a crucial component of wind power projects, serving as the primary support structure for the blades and main engine. Numerous supports and studs are welded to the inner wall of these piles to support and install internal accessories such as ladders, platforms, cable supports, and safety anchors. These supports and studs are welded to the pile wall, and the quality of this welding directly impacts the pile's service life. Therefore, the welds must be of high quality, and stress concentration caused by these support and stud welds must be eliminated.

[0003] Because the welding positions of the supports and studs to the cylinder wall are generally horizontal fillet welds, and are easily affected by the on-site working environment, weld appearance defects are prone to occur. These defects can easily cause stress concentration in the weld, leading to the failure of the entire pipe pile structure and reducing the service life of the tower. Therefore, it is necessary to treat the appearance of the weld to reduce stress concentration at the weld. The usual practice is to grind the weld, but this method is very likely to damage the base material, requiring repair welding at the defective areas, which is time-consuming, labor-intensive, and costly.

[0004] Based on this, this application proposes a low-stress welding joint process for wind turbine pipe pile structures, which makes the weld aesthetically pleasing, effectively reduces the residual stress of the weld, optimizes the fatigue resistance of the weld, improves the welding quality, and provides a guarantee for the operation of the wind turbine. Summary of the Invention

[0005] The purpose of this invention is to solve the problems of appearance defects, obvious stress concentration, and poor fatigue resistance in the welding of the inner wall support and studs of wind power pipe piles, as well as the problems of traditional grinding stress relief methods that easily damage the base material, are complicated and have low construction efficiency. The invention provides a low-stress welding joint process for wind power pipe pile structures.

[0006] This invention is achieved through the following technical solution: 1. A low-stress welding joint process for wind turbine pipe pile structures, used to weld studs or supports to the wall of the tower pipe pile, mainly including the following steps: a. Prepare the brackets or studs to be welded, grind the welding area to remove oxidation and rust, and expose the metal luster; at the same time, grind the welding area of ​​the tower pipe pile cylinder wall to remove oxidation and rust, and expose the metal luster. b. Preheat the welding area to at least 15°C; c. Use flux-cored wire arc welding (FCAW) for positioning welding to ensure accurate positioning dimensions; d. Welding is performed using flux-cored wire arc welding (FCAW) along the circumference of the support or stud, and the diameter of the welding wire used is 1.2 mm; e. Remove the flux and slag residue from the weld surface to make the surface clean; f. Use self-fusion tungsten inert gas (TIG) welding to weld the weld toe of the weld seam on one side of the tower pipe pile wall; no welding wire is needed, and the weld toe is self-fused by heating with a tungsten electrode.

[0007] As a further technical solution of the present invention, the welding parameters in step c are: current 180A~240A, voltage 26V~28V.

[0008] As a further technical solution of the present invention, the welding parameters in step d are: current 200A~260A, voltage 28V~29V.

[0009] As a further technical solution of the present invention, in step d, the welding position is a horizontal flat fillet weld position, and the weld thickness is 5mm.

[0010] As a further technical solution of the present invention, the tungsten electrode used in step f has a diameter of 3.0 mm and a nozzle diameter of 12 mm.

[0011] As a further technical solution of the present invention, when performing welding in step f, inert gas argon is used for protection, with argon purity ≥ 99.99% and gas flow rate 10L / min-18L / min.

[0012] As a further technical solution of the present invention, the welding parameters in step f are: current 190A-250A, voltage 16V-21V, and welding speed 210mm / min-240mm / min.

[0013] As a further technical solution of the present invention, the preheating temperature of the self-fluxing tungsten inert gas (TIG) welding is not lower than 150°C, the welding torch angle is 45°-90°, and the distance between the tungsten electrode and the weld toe is 0mm-2mm.

[0014] As a further technical solution of the present invention, in step f, the tungsten electrode direction during self-fusion welding should be close to the cylinder material, and the arc initiation position should avoid the corner edge.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. The joint formed by the present invention using flux-cored wire arc welding (FCAW) + self-fluxing tungsten inert gas welding (TIG) not only improves production efficiency and reduces production costs, but also ensures high quality and high strength of the weld, providing strong protection for the fatigue resistance and safety reliability of the project.

[0016] 2. This invention uses flux-cored wire arc welding (FCAW) to weld fillet welds, which is simple to operate, has a stable arc, produces beautiful welds, and is highly efficient; it also uses self-fluxing tungsten inert gas welding (TIG) to remove welding defects, reduce stress concentration at the weld toe and cylinder wall, and improve the fatigue resistance of the cylinder wall.

[0017] 3. This invention replaces the traditional post-weld grinding process with weld toe self-fusion, avoiding damage to the base material and repeated welding, simplifying the process, shortening the construction cycle, and significantly improving the production efficiency and economy of welding the inner wall accessories of wind power pipe piles. Attached Figure Description

[0018] Figure 1 Schematic diagram of the assembly structure of the stud and the tower pipe pile wall; Figure 2 Schematic diagram of arc welding of studs and flux-cored welding wire to the wall of tower pipe piles; Figure 3 Schematic diagram of self-fusion tungsten inert gas welding between studs and the tower pipe pile wall; Figure 4 Schematic diagram of the structure after welding the stud to the tower pipe pile wall.

[0019] In the diagram: 1. Stud; 2. Tower pipe pile wall. Detailed Implementation

[0020] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0022] like Figure 1-4 As shown in the figure, this specific embodiment discloses a low-stress welding joint process for wind turbine pipe pile structures, mainly applied to the welding operations of the pipe pile cylinder wall 2 and auxiliary components such as supports and studs 1 in offshore wind turbine towers. By combining flux-cored wire arc welding (FCAW) and self-fluxing tungsten inert gas welding (TIG), the residual stress and stress concentration of the weld are significantly reduced while ensuring welding strength, improving the fatigue resistance of the weld joint, and avoiding damage to the base material caused by traditional grinding processes, thus improving construction efficiency and welding quality stability. The main steps include: a. Pre-treatment of the welding areas of the supports or studs 1 and the tower pipe pile wall 2 to be welded. Prepare the supports or studs 1 to be welded, grind the welding area to remove oxidation and rust, and expose the metallic luster; at the same time, grind the welding area of ​​the tower pipe pile wall 2 to remove oxidation and rust, and expose the metallic luster; for rotating components such as studs 1, grind evenly along their circumferential welding surface to ensure a consistent welding interface state in the circumferential direction; for support components, focus on grinding the welding end face that contacts the pipe pile wall to ensure that the end face is flat, clean, and tightly fitted to the wall without gaps or warping.

[0023] b. Preheat the welding area to at least 15°C. Preheating can be done using flame heating or electric heating elements. The heating range should cover the welding area and its surrounding area, extending at least twice the plate thickness. During preheating, use a surface thermometer to measure the temperature at multiple points to ensure uniform preheating and avoid localized overheating or underheating. Insufficient preheating temperature can lead to the formation of hardened structures in the weld during rapid cooling, increasing residual stress and reducing the joint's fatigue resistance.

[0024] c. Use flux-cored wire arc welding (FCAW) for positioning welding to ensure accurate positioning dimensions and no positional deviation. The welding parameters in this step are: current 180A~240A, voltage 26V~28V.

[0025] d. Fillet welds are performed using flux-cored wire arc welding (FCAW). Welding is carried out along the circumference of the support or stud 1, using a 1.2mm diameter welding wire. The welding parameters for this step are: current 200A~260A, voltage 28V~29V. The welding position is a horizontal, downward-facing fillet weld. During welding, the welding torch angle is kept stable to avoid defects such as weld misalignment, undercut, and incomplete fusion caused by angular deviation. The fillet weld formed in this step is 5mm thick and serves as the main load-bearing connection between the support, stud 1, and the pipe pile wall. The fillet weld has uniform weld leg size and no obvious surface defects, ensuring the structural connection strength.

[0026] e. Remove flux residue and slag from the weld surface to ensure a clean surface. After the fillet weld has cooled to a suitable temperature, clean the weld surface using tools such as a wire brush and scraper to thoroughly remove flux residue, slag, metal spatter, and other residues, ensuring a clean and smooth weld surface. During cleaning, avoid damaging the weld body and surrounding base material to ensure a clear weld outline and provide good surface conditions for subsequent steps.

[0027] f. Use self-fusion tungsten inert gas (TIG) welding to weld the weld toe area on one side of the tower pipe pile wall 2. No welding wire is needed; the tungsten electrode heats the weld toe area for self-fusion. In this step, a 3.0mm diameter tungsten electrode is used, paired with a 12mm diameter gas nozzle. The shielding gas is high-purity argon with a purity of not less than 99.99%, and the gas flow rate is controlled at 10L / min–18L / min to ensure good gas shielding and prevent oxidation and nitriding of the weld toe area at high temperatures. The welding parameters for this step are: welding current 190A–250A, welding voltage 16V–21V, and welding speed 210mm / min–240mm / min. Before welding, the weld toe area is preheated to a temperature not lower than 150℃ to further reduce welding stress and cold cracking tendency. During the self-fusion welding process, the welding torch angle is maintained at 45°–90°, and the tungsten electrode tip is 0mm–2mm away from the weld toe area to ensure concentrated arc and uniform heating. The tungsten electrode should be positioned closer to the cylinder material to allow more molten metal to transition towards the cylinder wall, optimize the weld toe transition radius, and reduce the stress concentration factor. The arc initiation position should avoid the weld corner edge to prevent defects such as undercut and arc crater caused by current impact during arc initiation. When ending the arc, slowly fill the arc crater to avoid the formation of arc crater cracks. Example 1

[0028] A low-stress welding joint process for wind turbine pipe pile structures, used to weld M16 studs 1 to the inner side of the wall 2 of Q355B offshore wind turbine tower pipe pile, the specific steps are as follows: a. The circumferential welding surface of the M16 stud 1 and the welding area of ​​the tower pipe pile cylinder wall 2 to be welded are ground with an angle grinder to remove surface oxide scale, rust, oil and impurities until a uniform and bright metallic luster is exposed. The grinding range covers the weld area and the surrounding 15mm.

[0029] b. Preheat the welding area using flame heating, and use a temperature measuring instrument to detect the temperature. The preheating temperature is controlled at 25℃.

[0030] c. Use flux-cored wire arc welding (FCAW) for positioning welding. Select 1.2mm diameter flux-cored wire, welding current 210A, welding voltage 27V to complete the positioning of stud 1, ensuring accurate, firm and non-shifted position.

[0031] d. Continuous fillet welds are made along the circumference of stud 1 using flux-cored wire arc welding (FCAW). The welding position is a horizontal, downward-facing fillet weld position. The welding current is 230A, the welding voltage is 28.5V, the wire diameter is 1.2mm, and a uniform fillet weld with a thickness of 5mm is formed.

[0032] e. After the weld has cooled to room temperature, use a wire brush to clean the weld surface of flux, slag and metal spatter to ensure that the weld surface is clean and free of impurities.

[0033] f. Use self-fusion tungsten inert gas (TIG) welding to remelt the weld toe on one side of the cylinder wall without adding welding wire; use a 3.0 mm diameter tungsten electrode and a 12 mm nozzle diameter; use 99.99% pure argon gas with a flow rate of 14 L / min; preheat the temperature to 150℃; use a welding current of 220 A, a welding voltage of 18 V, and a welding speed of 220 mm / min; use a welding torch angle of 60°, keep the tungsten electrode 1 mm away from the weld toe, and position the tungsten electrode towards the side of the cylinder material. Avoid the corner edge when starting the arc and perform self-fusion treatment along the entire length of the weld toe. Example 2

[0034] A low-stress welding joint process for wind turbine pipe pile structures, used to weld steel supports to the wall 2 of offshore wind turbine tower pipe piles, includes the following specific steps: a. Grind the welded end face of the support and the welded area of ​​the pipe pile wall to remove oxidation and rust, exposing the metallic luster. The grinding range covers the weld and the surrounding 15mm.

[0035] b. Use electric heating elements to preheat the welding area to 30°C, ensuring a uniform and stable temperature.

[0036] c. Positioning welding is performed using flux-cored wire arc welding with a welding current of 200A, a voltage of 26V, and a wire diameter of 1.2mm. The positioning is firm and without deformation.

[0037] d. Continuous fillet welds are made along the outline of the support using flux-cored wire arc welding. The welding position is a horizontal, downward-facing fillet weld position. The welding current is 240A, the voltage is 29V, the weld leg size is uniformly 5mm, and the weld formation is full and beautiful.

[0038] e. After the weld has cooled, use a wire brush and scraper to clean the slag, flux, and spatter from the weld surface to ensure a clean weld surface.

[0039] f. The weld toe is subjected to self-fusion treatment using self-fusion tungsten inert gas (TIG) welding. The argon purity is 99.99% and the flow rate is 12 L / min. The welding current is 230 A, the voltage is 19 V, and the welding speed is 230 mm / min. The welding torch angle is 75°, the distance between the tungsten electrode and the weld toe is 1 mm, the preheating temperature is 150 °C, the tungsten electrode is biased towards one side of the cylinder wall, and the arc starting point avoids the corner edge to complete the self-fusion smooth treatment of the entire weld toe.

[0040] After welding, the welded joints of Examples 1 and 2 were visually inspected and their performance verified. The results showed that the weld surface was smooth and flat, free from defects such as porosity, slag inclusions, undercut, and cracks. The weld toe transition was smooth, the residual stress level was significantly reduced compared to traditional welding processes, and the fatigue resistance was significantly improved. Compared with traditional post-weld grinding processes, this process avoids damage to the base material and the need for repair welding, and can meet the service requirements of offshore wind turbine piles under long-term, heavy-load, and alternating loads, effectively reducing the risk of structural failure and providing a reliable guarantee for the safe and stable operation of wind turbines.

Claims

1. A low-stress welding joint process for wind turbine pipe pile structures, used to weld studs (1) or brackets to the tower pipe pile cylinder wall (2), characterized in that, The main steps include: a. Prepare the bracket or stud to be welded (1), grind the welding area to remove oxidation and rust, so that it exposes the metal luster; and at the same time grind the welding area of ​​the tower pipe pile wall (2) to remove oxidation and rust, so that it exposes the metal luster. b. Preheat the welding area to at least 15°C; c. Use flux-cored wire arc welding (FCAW) for positioning welding to ensure accurate positioning dimensions; d. Welding is performed using flux-cored wire arc welding (FCAW). The welding is performed along the circumference of the support or stud (1). The diameter of the welding wire used is 1.2 mm. The welding position is a horizontal flat fillet weld position. The weld thickness is 5 mm. e. Remove the flux and slag residue from the weld surface to make the surface clean; f. Use self-melting tungsten inert gas (TIG) welding to weld the weld toe of the weld edge on one side of the tower pipe pile wall (2); no welding wire is needed, and the self-melting of the weld toe is achieved by heating with a tungsten electrode; the diameter of the tungsten electrode used is 3.0 mm; the diameter of the nozzle is 12 mm.

2. The low-stress welding joint process for wind power pipe pile structures as described in claim 1, characterized in that, The welding parameters in step c are: current 180A~240A, voltage 26V~28V.

3. The low-stress welding joint process for wind power pipe pile structures as described in claim 1, characterized in that, The welding parameters in step d are: current 200A~260A, voltage 28V~29V.

4. The low-stress welding joint process for wind power pipe pile structures as described in claim 1, characterized in that, During the welding in step f, an inert gas argon is used for protection, with an argon purity ≥ 99.99% and a gas flow rate of 10 L / min - 18 L / min.

5. The low-stress welding joint process for wind power pipe pile structures as described in claim 1, characterized in that, The welding parameters in step f are: current 190A-250A, voltage 16V-21V, and welding speed 210mm / min-240mm / min.

6. The low-stress welding joint process for wind power pipe pile structures as described in claim 1, characterized in that, The preheating temperature for the self-fluxing tungsten inert gas (TIG) welding is not lower than 150°C, the angle of the welding torch is 45°-90°, and the distance between the tungsten electrode and the weld toe is 0mm-2mm.

7. The low-stress welding joint process for wind power pipe pile structures as described in claim 1, characterized in that, In step f, the tungsten electrode direction during autofusion welding should be close to the cylinder material, and the arc initiation position should avoid the corner edge.

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