Method for welding tower drum and foundation ring of wind generating set

Abstract

The invention discloses a welding method for a tower drum and a foundation ring of a wind generating set. Comprising the following steps: a welding preparation stage: carefully selecting and treating materials, strictly debugging equipment and carefully preparing weldments; in the welding implementation stage, an argon-rich mixed gas shielded welding method is determined, welding process parameters are optimized, and the welding processes of a single-section longitudinal seam and a flange, two small-section assembly, large-section assembly length, an inner circular seam and an outer circular seam are accurately controlled; in the welding quality control stage, welding parameters are monitored and adjusted in real time, and appearance inspection after welding, RT ray inspection, mechanical property testing and metallographic testing are strictly conducted; and the production practice and optimization stage is applied to actual production, problems are tracked and solved, and the process is continuously optimized to improve the quality. The method effectively improves the welding quality and the production efficiency, enhances the structural stability, reduces the cost and promotes the development of the wind power industry.

Description

Technical Field

[0001] The invention relates to the field related to tower welding of a wind turbine generator set, and in particular to a tower and foundation ring welding method of a wind turbine generator set. Background Art

[0002] As the global demand for clean energy continues to increase, wind power generation has been widely used as a sustainable energy solution. The tower and foundation ring of wind turbines are important supporting structures of wind power generation systems, and their welding quality is directly related to the safety, stability and service life of the entire unit.

[0003] At present, the welding of wind turbine towers and foundation rings faces many challenges. On the one hand, tower structures are mostly super-large structures, which have extremely high requirements for welding technology. For example, their bearing capacity and stability requirements require the welded joints to have high strength and good toughness. On the other hand, there are some problems when traditional welding methods are applied to tower and foundation ring welding. For example, the commonly used manual arc welding and CO2 gas shielded welding, although the technology is relatively mature, are prone to large welding deformation and many welding defects during the welding process. In addition, the welding efficiency is low, and the labor and electricity costs account for a high proportion. According to statistics, in the entire manufacturing process of wind towers and foundation rings, more than 65% of the time is spent on the welding process, and the labor and electricity costs account for more than half of the production costs.

[0004] In order to improve the welding quality and production efficiency of wind turbine towers and foundation rings, reduce costs, and meet the growing needs of the wind power industry. Summary of the invention

[0005] The object of the present invention is to provide a method for welding a tower and a foundation ring of a wind turbine generator set to solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: a method for welding a tower and a foundation ring of a wind turbine generator set, comprising the following steps: Step 1: Welding preparation stage Q345E steel is selected as the tower base material, and its chemical composition is analyzed to ensure that it meets the corresponding standards, including C content of 0.18%, Mn content of 1.00-1.60%, Si content less than 0.55%, P content less than 0.025%, S content less than 0.025%, V content of 0.02-0.15%, Nb content of 0.015-0.06%, and Ti content of 0.02-0.20%; Welding materials are strictly screened. Arc welding electrodes are E5015-G with a diameter of 3.2mm; CO2 gas shielded welding electrodes are TH550-N with a diameter of 2.0mm; argon-rich mixed gas shielded welding electrodes are ER50-6 with a diameter of 1.2mm. All welding materials are re-inspected by batch before use to ensure that their performance meets the requirements, including yield strength>355MPa, elongation>20%, and the performance of welding and heat-affected areas is not less than 80% of the parent material; Welding equipment debugging: Select appropriate welding equipment and debug the equipment to normal working state to ensure that parameters such as welding current, voltage, gas flow rate, etc. can be stably adjusted; Cut the tower mother material, use plasma cutting or oxyacetylene cutting for steel plates, process the incision area and gap after cutting, remove burrs and oxide layers, chamfer the holes, and ensure that the verticality and inclination tolerances of the cutting surface meet the requirements; increase the purity of cutting oxygen to more than 99.5%, and use liquid oxygen to improve cutting quality and speed; optimize the cutting speed and adjust it according to actual conditions to ensure the cutting effect; Process the steel plate after rolling. When rolling, the direction of the roller should be consistent with the rolling direction of the steel plate. Clean the debris on the surface of the steel plate. Make samples according to the cylinder diagram to avoid mechanical damage. Ensure that the roller is well connected during butt welding. Clean the oxides at the spot welding. The gap between the butt plates is 0.5-2mm. The vertical edge error is not greater than the nominal wall thickness and the maximum is 3mm. After the initial formation of the cylindrical section, spot welding is performed first and then submerged arc welding. After welding, adjust the pipe section and test it with a ruler. Step 2: Welding implementation stage The welding method is determined as follows: argon-rich mixed gas shielded welding is used for welding, wherein the shielding gas is 80% Ar + 20% CO2; the welding current is 220-280A; the welding speed is 300-500mm / min; the gas flow rate is 15-20L / min; Optimization of welding process parameters Energy line selection: Calculate energy line according to the formula q=IU / v, set energy line to 1.71KJ / cm, where welding current I is 220-280A, arc voltage U is 24-30V, welding speed v is 300-500mm / min, to ensure that the tensile strength of the welded joint is high, the softening phenomenon of the heat-affected zone is relatively light, and the microstructure of the weld zone is acicular ferrite, martensite and ferrite; Selection of droplet transfer form: Jet transfer mode is adopted, and the welding process parameters are welding current 120-220A, voltage 17-18V, welding speed 300±50mm / min, gas flow 15-20L / min, to ensure high quality of weld formation and less spatter; Single section longitudinal seam and flange welding Use suspended submerged arc welding to weld a single longitudinal seam, and reserve a 5mm flange to compensate for axial deformation. According to theoretical analysis and experimental measurement, the cylindrical welding volume shrinks by about 7.64mm. The blank body height and flange thickness are adjusted accordingly to reduce material and processing workload and optimize the welding production site. The tailor-welded flange is welded with a partial anti-deformation solution. The first two circles are spot welded first. The arc plate and the welding arc plate are deformed and filled into a group. Then the large arc plates of the adjacent groups are welded and deformed. Finally, two half arc plates are welded into a complete flange. During the welding process, communication is used to further reduce welding deformation, ensure the overall roundness of the flange and make timely adjustments, and optimize the welding production site. Two-section welding Use 20% CO2 + 80% Ar as welding shielding gas, reduce welding voltage to 22-33V to reduce spatter; at the same time, increase the content of Ti, Al and other elements in the welding rod appropriately, or improve the control form of the welding machine, such as using CO2-CO2, PS-CO2 control method, or coat the workpiece surface, choose appropriate powder to prevent spraying, so as to further reduce spatter; The roller frame is assembled into two sections of cylinders through the FUB40 two-section pipe assembly. Four groups of roller frames are installed on the integral base. The hydraulic cylinder is used to adjust the butt clearance and misalignment. The active roller frame is driven by an AC motor through a reducer. It runs smoothly, has high efficiency, and has a large transmission torque. The inverter is used for speed regulation. The roller frame is annealed and sandblasted after welding. The special tooling platform for two-section assembly is optimized to improve welding efficiency and reduce the workload of workers. Large section butt welding and inner circumferential seam welding A 40-ton hydraulic group and an 80-ton adjustable walking roller frame are used to connect the large sections of the cylinder. A 1250A submerged arc welding trolley is used for inner girth welding. The weld joints are optimized and the weld surface is changed to a convex shape to offset some tensile stress and reduce the generation of thermal cracks. The original acid electrodes are considered to be replaced by more desulfurized alkaline electrodes A307 and A107, and the chemical composition of both is consistent with DC reverse phase. Outer seam welding Double-sided double-arc welding is used to weld some welds that need to be cleaned and welded through. The equipment consists of CZ22-6x5 welding manipulator, 1250A suspended submerged arc welding system, 80-ton adjustable walking roller frame, etc. It is used for welding the outer ring seam after the long-length assembly of large sections of the cylinder. The production line equipment is reasonably planned, and the work site is ready before the assembly is completed; The non-grooved overlap form is used instead of the 16x45° grooved connection form on the cylinder round gasket to improve the heat input and sedimentation rate of the unit. The double arc gas protection is used to avoid the post-welding cleaning process, simplify the welding process, and reduce the occurrence of inclusions. Step 3: Welding quality control stage Process monitoring and adjustment During the entire welding process, the welding parameters are strictly controlled to ensure that the welding process is smooth and carried out in a straight line. The welding speed is controlled within the preset range and the deposition ratio is controlled between 1.3-1.5. Strengthen slag removal work, especially on the surface of butt weld layer, to control inclusion defects and ensure welding quality; Post-weld inspection and treatment Carry out visual inspection on the welded tower and foundation ring, including welding defects and weld shape defects; RT ray inspection is used to conduct nondestructive testing on the inside of the weld. By utilizing the ray projection characteristics of the material and the differences in the absorption and attenuation of x-rays by different materials, the photos are made into different blackness of the images to observe the internal structure; Conduct mechanical property tests on welded joints, including tensile test, bending test, and impact test, to ensure that the mechanical properties of welded joints meet the requirements; Metallographic tests were carried out to examine the metallographic structures of the weld center, overheating zone, and quenching zone, the dendritic segregation, lamellar segregation, and regional segregation of weld metal, the organizational structure of areas with different organizational characteristics, the changes in the organization and properties on both sides of the fusion line of dissimilar joints, and the ferrite content in Q345E steel welds.

[0007] Furthermore, during the welding preparation stage, when pre-treating the Q345E steel base material, if the steel plate has overall edge bending and local lifting deformation during transportation, storage, cooling, and rolling that affects the cutting quality, the steel plate needs to be corrected before cutting to ensure that the steel plate is in a flat state during cutting, so as to improve the cutting accuracy and ensure the smooth progress of the subsequent welding process.

[0008] Furthermore, during the welding implementation stage, when using argon-rich mixed gas shielded welding, the welding area needs to be cleaned before welding to remove oil, rust and other impurities to prevent impurities from entering the weld during the welding process and affecting the weld quality, thereby ensuring that the performance of the welded joint meets the requirements.

[0009] Furthermore, during the welding process of single-section longitudinal seams and flanges, for the suspended submerged arc welding equipment, the parameters of the welding operator, suspended submerged arc welding system, manually adjustable roller frame, and inclined roller frame equipment need to be precisely adjusted according to the specific size of the tower and welding requirements to ensure a stable welding process, good weld formation, and improved welding quality and production efficiency.

[0010] Furthermore, during the two-section assembly welding process, the hydraulic cylinder of the FUB40 two-section pipe assembly roller frame must operate according to a precise control procedure when adjusting the butt clearance and misalignment between the two cylinders to ensure that the butt clearance is controlled within the range of 0.5-2mm and the misalignment does not exceed the specified value, thereby ensuring assembly accuracy and improving welding quality.

[0011] Furthermore, during the long-section assembly and inner ring seam welding process, the 40-ton hydraulic assembly roller frame and the 80-ton adjustable walking roller frame need to use a high-precision positioning system when moving and positioning the cylinder to ensure that the cylinder docking position is accurate and the deviation does not exceed the allowable range, providing good conditions for the inner ring seam welding and ensuring the welding quality.

[0012] Furthermore, during the welding quality control stage, if defects are found inside the weld during the RT ray inspection, appropriate repair measures must be taken according to the type and severity of the defects. For example, small pore defects can be repaired by repair welding and re-inspection can be performed to ensure that the internal quality of the weld meets the requirements.

[0013] Furthermore, during the mechanical properties test, the preparation of specimens for tensile tests, bending tests and impact tests must be carried out strictly in accordance with standard specifications to ensure that the specimen size is accurate and the surface is smooth. During the test, test equipment with precision that meets the requirements must be used and accurate data must be recorded to ensure the reliability of the test results and accurately evaluate the mechanical properties of the welded joint.

[0014] Furthermore, during the production practice and optimization stage, while tracking the production process simultaneously, it is necessary to establish a detailed welding quality record file to record the various parameters, test results, problems encountered and solutions during the welding process, so as to conduct a systematic analysis and continuous optimization of the welding process and improve the overall welding quality and production efficiency.

[0015] Furthermore, during the entire welding process, the welding environment temperature and humidity need to be monitored and controlled. When the ambient temperature is lower than 5°C, appropriate preheating measures need to be taken to ensure that the temperature in the welding area meets the requirements; when the humidity exceeds 90%, dehumidification measures need to be taken to prevent porosity defects in the weld and ensure stable welding quality.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This welding method ensures a good match between the welding material and the parent material by accurately selecting the welding material, such as selecting welding rods of specific models and specifications for different welding methods, and strictly re-inspecting them, thereby improving the strength and toughness of the welded joint.

[0017] Optimized welding process parameters, such as specific gas ratio, welding current, speed and gas flow in argon-rich mixed gas shielded welding, as well as appropriate line energy and droplet transition form, make the weld shape beautiful, reduce the occurrence of welding defects, and improve the quality of the weld joint.

[0018] Strict pre-welding preparation, including precise cutting and coiling of steel plates, as well as debugging of welding equipment, provides good basic conditions for high-quality welding.

[0019] In the welding of single-section longitudinal seams and flanges, measures such as reserved deformation and anti-deformation schemes are adopted to effectively control welding deformation, ensure the dimensional accuracy of the tower and flanges, and improve the overall stability of the structure.

[0020] The optimization of the butt joints and inner circumferential welds of large sections, such as changing the weld surface to a convex shape, reduces the occurrence of thermal cracks and enhances the reliability of the structure when subjected to loads such as wind.

[0021] The selection of suitable welding equipment and optimized welding process parameters, such as higher welding current and speed, shortens the welding time and improves production efficiency.

[0022] Reasonable planning of welding procedures, such as the use of advanced roller rack equipment and optimized assembly process in the two-section assembly welding, reduces workers' operation time and labor intensity and improves overall production efficiency.

[0023] Improving welding quality and production efficiency, reducing rework and material waste caused by welding defects, and reducing production costs. High-quality tower and foundation ring welding methods help improve the overall performance and reliability of wind turbines, extend their service life, and reduce maintenance costs, thereby promoting the sustainable development of the wind power industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0025] See also Figure 1 The present invention provides a method for welding a tower and a foundation ring of a wind turbine generator set, comprising the following steps: 1. Welding preparation stage Q345E steel is selected as the parent material of the wind turbine tower. Q345E steel is a low alloy steel with good comprehensive mechanical properties. Its tensile strength is between 470-630MPa, its yield strength is not less than 325MPa, its elongation is not less than 22%, and its impact energy is not less than 27J at -40°C. Its chemical composition includes 0.18% C, 1.00-1.60% Mn, less than 0.55% Si, less than 0.025% P, less than 0.025% S, 0.02-0.15% V, 0.015-0.06% Nb, and 0.02-0.20% Ti. The reasonable ratio of these elements makes Q345E steel have high strength, good low temperature toughness and welding performance.

[0026] When purchasing materials, we strictly check the quality certification documents of steel to ensure that the chemical composition and mechanical properties of steel meet the standard requirements. We conduct random inspections on each batch of steel, use the MaxxLMM14 portable direct reading spectrometer to detect the chemical composition of steel, and use the MTS370.25 material testing machine to test the mechanical properties to ensure the stable and reliable quality of steel.

[0027] The arc welding electrode is E5015-G, with a diameter of 3.2 mm. This electrode has good welding process performance, can be operated in different welding positions, and the weld metal has high strength and toughness.

[0028] The CO2 gas shielded welding electrode is TH550-N with a diameter of 2.0 mm. It is characterized by high deposition efficiency and fast welding speed. It is suitable for welding thicker plates and can meet the needs of large workloads in wind tower welding.

[0029] The argon-rich mixed gas shielded welding electrode is ER50-6 with a diameter of 1.2mm. Under the protection of argon-rich mixed gas, this electrode can obtain good weld formation and mechanical properties and reduce welding spatter.

[0030] All welding materials are re-inspected by batch before use. For welding rods, check whether there are defects such as cracks and pores on their appearance, and analyze their chemical composition to ensure that they meet the relevant standards. For welding wires, check their diameter deviation, surface quality, etc. At the same time, the mechanical properties test of the deposited metal is carried out in accordance with relevant standards, including tests such as tensile strength, yield strength, elongation and impact energy, to ensure that the performance of the welding materials in the welding and heat-affected zones is not less than 80% of the parent material, and the Charpy V-notch effect work in the welding and heat-affected zones meets the standard requirements of GB / T1591-2008.

[0031] Select MIG / MAG arc welding power source, model YD-500KR, for welding. During the debugging process, first check whether the appearance of the power source is intact and whether the connection line is firm. Then turn on the power source, check whether the display screen of the power source is normal, and whether the knobs for adjusting the welding current and voltage are flexible.

[0032] Run the power supply without load for a period of time to observe whether the power supply has abnormal heating, noise, etc. Use professional electrical testing instruments: oscilloscope, multimeter, to detect the current and voltage waveforms output by the power supply to ensure that they are stable and without distortion.

[0033] According to the welding process requirements, set different welding current and voltage values, check whether the power supply output is accurate and the error is controlled within the allowable range.

[0034] For M0618A grinder and DK7740 CNC EDM wire cutting machine, check whether its moving parts are flexible and whether the fixture on the workbench can firmly clamp the workpiece. Adjust the grinding wheel speed and feed system of the grinder to ensure that it can meet the processing requirements of different precision. For CNC EDM wire cutting machine, check the installation and tension of its electrode wire, adjust the cutting program, and ensure that it can accurately cut according to the predetermined path.

[0035] When debugging the TYM-2 metallographic sample pre-grinding machine and the TYMP-2B metallographic sample grinding and polishing machine, check the flatness of the grinding and polishing discs, adjust the speed and pressure, and ensure that high-quality pre-grinding and polishing can be performed on the metallographic samples.

[0036] When commissioning the MTS material fatigue tester and the MTS pendulum impact tester, check whether the sensor is sensitive and whether the loading system is working properly. Calibrate the tester, use standard specimens for testing, and compare the test results with the standard values ​​to ensure that the accuracy of the tester meets the requirements.

[0037] The steel plate is cut by plasma or oxyacetylene. Before cutting, according to the design requirements, AutoCAD2010 software is used for precise lofting to determine the cutting path and size. For oxyacetylene cutting, the purity of oxygen has an important influence on the cutting quality and speed. Try to increase the purity of cutting oxygen to more than 99.5%. Liquid oxygen can be used to reduce the influence of impurity oxygen (nitrogen) during the cutting process, prevent it from absorbing heat to form a cutting gas film, and hinder the process of burning metals and oxides, thereby increasing the cutting speed, reducing the cutting width, and reducing the surface roughness, cutting edge and slag.

[0038] After cutting, treat the cut area and gaps. Use grinding tools to remove burrs from the cut to make the surface smooth and avoid affecting the quality of subsequent welding. For the oxide layer, mechanical or chemical methods are used to remove it. Chamfer holes, bolt holes and reaming holes to remove sharp edges around them to prevent stress concentration. After cutting the reinforcement holes (elliptical holes), all visible traces of the grooves must be removed to ensure that there are no cracks or gaps around the holes. If welding is used to repair welding defects, strictly follow the application rules and conduct corresponding tests.

[0039] Ensure that the tolerance of verticality and steel weld surface meets the requirements specified in JB / T5000.2-2007. Select the appropriate tolerance grade according to the cutting thickness. For example, when the cutting thickness is 6-10mm, the verticality tolerance is 0.5mm; when the cutting thickness is 10-20mm, the verticality tolerance is 0.6mm, etc. During the cutting process, CNC flame cutting technology is used to optimize cutting parameters such as cutting speed, oxygen pressure, etc., and adjust them according to the material and thickness of the steel plate to ensure cutting accuracy.

[0040] When rolling, the roller direction is consistent with the rolling direction of the steel plate to ensure that the steel plate is evenly stressed during the rolling process to avoid wrinkles or deformation. Before rolling, clean the surface of the steel plate, such as rust, oil, etc., and use sandblasting, pickling and other methods to ensure that the surface of the steel plate is clean and improve the welding quality.

[0041] According to the requirements of the cylinder diagram, different samples are made to detect the size and shape accuracy after rolling. In the process of rolling the steel plate surface, mechanical damage is avoided, and the damage caused by the grinding part is repaired in time to make it smooth. The wall shall not exceed the nominal wall thickness of the maximum defect depth function, that is, the thickness of the steel plate is less than 1mm.

[0042] When butt welding, the rollers should be connected, and the oxides and other debris should be cleaned at the spot welding to ensure the welding quality. When spot welding, control the welding current and time to ensure that the welding point is firm. The gap of the butt plate is controlled between 0.5-2mm, and the vertical edge error is not greater than the nominal wall thickness, and the maximum is 3mm (t is the thickness of the steel plate, mm). After spot welding, submerged arc welding is performed, and the welding parameters are adjusted to ensure that the weld is well formed. After welding, adjust the pipe section and use a ruler to test its roundness, diameter and other dimensions to ensure that it meets the design requirements.

[0043] 2. Welding implementation stage The welding is carried out by argon-rich mixed gas shielded welding, and the shielding gas is 80% Ar + 20% CO2. The welding current is 220-280A. Within this current range, the weld penetration can be guaranteed to be moderate. The welding speed is 300-500mm / min, which can be adjusted appropriately according to the thickness of the plate and the welding position. The gas flow rate is 15-20L / min to ensure that the shielding gas can effectively cover the welding area, prevent air intrusion, and reduce welding defects. Before welding, clean the welding area to remove impurities such as oil and rust. Solvent cleaning and grinding can be used. At the same time, check the gas delivery system of the welding equipment to ensure that the gas flow is stable and leak-free.

[0044] Line energy selection The line energy is calculated according to the formula q=IU / v, and the line energy is set to 1.71KJ / cm. The welding current I is 220-280A, the arc voltage U is 24-30V, and the welding speed v is 300-500mm / min. In actual operation, the welding current, voltage and speed are accurately adjusted according to factors such as plate thickness and welding position to ensure that the line energy is stable near the set value.

[0045] When welding thicker plates, appropriately increase the welding current and voltage, and reduce the welding speed to ensure that the weld penetration and width meet the requirements, and avoid excessive line energy leading to aggravated softening of the heat-affected zone. For thinner plates, reduce the welding current and voltage accordingly, increase the welding speed, and prevent burn-through.

[0046] Selection of droplet transfer form The jet transfer method is adopted, and the welding process parameters are welding current 120-220A, voltage 17-18V, welding speed 300±50mm / min, and gas flow 15-20L / min. During the welding process, the welding current and voltage are adjusted to make the molten droplet transfer present a jet state.

[0047] Observe the weld formation to ensure that the weld surface is smooth, the width is uniform, and there are no spatter particles. If the weld formation is poor or there is a small amount of spatter, fine-tune the welding current and voltage to achieve the best jet transition state. At the same time, ensure that the gas flow is stable to prevent the fluctuation of gas flow from affecting the droplet transition and weld protection effect.

[0048] Single section longitudinal seam and flange welding Suspended submerged arc welding is used to weld the single longitudinal seam, and CZ02-6x4 welding manipulator, 1250A suspended submerged arc welding system, JT-20 manual machine adjustment roller frame, BKT-20 tilting roller frame and other equipment are selected. Before welding, according to the axial size (4000mm) and design requirements of SE11520C high-speed permanent magnet wind turbine after production, a 5mm flange is reserved to compensate for axial deformation. Through theoretical analysis and experimental measurement, the cylindrical welding volume shrinks by about 7.64mm, and the blank main body height of the corresponding adjustment tube is adjusted from 1050mm to 1055mm, and the flange thickness is cut from 82mm to 80mm.

[0049] During the welding process, the welding sequence and direction are controlled, and methods such as segmented back-welding are used to reduce the accumulation of welding stress. At the same time, the rotation of the roller frame is used to evenly heat the weld and further reduce deformation. After welding, the axial and radial deformation of the tower is measured, and the measurement data is compared with the design requirements using measuring instruments such as total stations and levels to ensure that the deformation is within the allowable range.

[0050] Control of warpage deformation of tailor-welded flange A partial anti-deformation solution is adopted. The first two circles are spot welded first. The arc plate and the welding arc plate are deformed and filled into a group. Then the large arc plates of the adjacent groups are welded and deformed. Finally, two half arc plates are welded into a complete flange. During the welding process, the welding deformation is further reduced through communication, such as real-time monitoring of the welding deformation and timely adjustment of the welding parameters according to the deformation data.

[0051] Ensure the overall roundness of the flange, use a roundness measuring instrument to measure, and adjust the welding sequence and parameters in time to ensure that the roundness error does not exceed the specified value. Optimize the welding production site, arrange the welding equipment and workpieces reasonably, and ensure that the welding operation is convenient and efficient.

[0052] Two-section welding Use 20% CO2 + 80% Ar as welding shielding gas, and reduce welding voltage to 22-33V to reduce spatter. Before welding, check the gas mixing device to ensure the correct gas ratio. At the same time, select the appropriate voltage value according to the electrode diameter and welding current, and determine the best voltage parameters through experiments.

[0053] The content of elements such as Ti and Al in the welding rod can be appropriately increased, and the formula can be adjusted during the manufacturing process of the welding rod. Improve the control form of the welding machine, such as using CO2-CO2 and PS-CO2 control methods, and control the metallurgical reaction and transition process by adjusting the output current of the welding power supply. When coating the surface of the workpiece, choose suitable powder (such as ceramic powder) to prevent spraying, spray the powder evenly on the surface of the workpiece, control the thickness within a certain range, and determine the optimal coating thickness through experiments.

[0054] Cylinder assembly and welding The two-section cylinders are assembled by roller frames using the FUB40 two-section pipe assembly. Four sets of roller frames are installed on the integral base, and the butt clearance between the two cylinders is adjusted using hydraulic cylinders. The two sets of driven roller frames near the weld side of the two cylinders have hydraulic assembly functions, and the rollers can be lifted up and down by hydraulic cylinders to adjust the misalignment of the two cylinders to achieve the purpose of assembly.

[0055] The active roller frame roller is driven by an AC motor through a reducer. The entire transmission system runs smoothly, with high efficiency and large transmission torque. The frequency converter is used to adjust the speed of the roller frame according to the welding process requirements. The roller frame is annealed after welding to eliminate welding stress and sandblasted to improve surface quality and long service life. The two-section assembly special tooling platform is optimized to ensure that the flatness and positioning accuracy of the tooling platform meet the requirements, so that the welding efficiency and the workload of workers are significantly reduced.

[0056] Large section butt welding and inner circumferential seam welding A 40-ton hydraulic group and an 80-ton adjustable walking roller frame are used to butt-join the large sections of the cylinder, and a 1250A submerged arc welding trolley is used for inner circumferential seam welding. The weld joints are optimized and the weld surface is changed to a convex shape to offset some tensile stress and reduce the generation of thermal cracks. Before welding, a suitable welding groove is designed and made to ensure that the root of the weld can be welded through, while controlling the groove angle and blunt edge size to reduce the amount of welding filling.

[0057] Consider replacing the original acidic electrode with more desulfurized alkaline electrodes A307 and A107, both of which have the same chemical composition as DC reverse phase. When replacing the electrode, adjust the welding current and voltage parameters and optimize them according to the characteristics of the electrode to ensure a stable welding process and good weld quality.

[0058] During the welding process, control the welding heat input, and reasonably adjust the welding current, voltage and welding speed according to the plate thickness and welding position to avoid excessive heat input leading to thermal cracks. At the same time, keep the welding environment clean to prevent dust, impurities, etc. from entering the welding area.

[0059] The multi-layer and multi-pass welding process is adopted, and the thickness of each layer of weld is controlled within a certain range. The overlapping part between each weld meets the requirements to ensure that the weld is well formed and has no defects such as slag inclusion and pores. After welding is completed, the weld is visually inspected and defects are repaired in time.

[0060] Outer seam welding Double-sided double arc welding is used to weld some welds that need to be cleaned and welded through. The equipment consists of CZ22-6x5 welding manipulator, 1250A suspended submerged arc welding system, 80-ton adjustable walking roller frame, etc. Before welding, the welding equipment is debugged to ensure the synchronization of the double arc welding gun and the consistency of welding parameters.

[0061] According to the weld position and plate thickness, the spacing and angle of the double arc welding guns are reasonably adjusted to ensure good fusion of the welds on both sides when welding at the same time, thus improving welding efficiency and quality. During the welding process, the weld formation is closely observed and the welding parameters are adjusted in time to ensure the appearance and internal quality of the weld.

[0062] The lap joint without slotting is used to replace the 16x45° slotted connection on the cylinder round gasket, which improves the heat input and sedimentation rate of the unit. The double arc gas protection is used to avoid the post-welding cleaning process, simplify the welding process, and reduce the occurrence of inclusions. When designing the welding process, the parameters such as the lap length and gap are optimized, and the optimal parameter values ​​are determined through experiments.

[0063] Before welding, clean the overlapped parts to ensure that there is no oil, rust or other impurities on the surface. During welding, control the welding current, voltage and welding speed to make the weld evenly fused without defects such as false welds and leaks. After welding, perform visual inspection and non-destructive testing on the weld to ensure welding quality.

[0064] 3. Welding quality control stage During the entire welding process, a welding parameter monitor is used to monitor welding current, voltage, welding speed, gas flow and other parameters in real time. The parameter alarm range is set, and when the parameter exceeds the normal range, an alarm is issued in time to remind the operator to make adjustments.

[0065] Record welding parameters at regular intervals to form a welding parameter record report for subsequent analysis of the stability and consistency of the welding process. Analyze abnormal parameter conditions, find out the causes, such as equipment failure, human error, etc., and take corresponding corrective measures.

[0066] Strengthen the slag removal work, especially on the surface of the butt weld layer. During the welding process, use the slag removal tool to remove the slag on the weld surface in time after each layer of welding is completed, and check whether there are defects such as pores, cracks, and lack of fusion on the weld surface.

[0067] Defects found should be marked in time, and corresponding treatment measures should be taken according to the defect type and severity. For example, for small pores, the method of grinding and then welding can be adopted; for cracks, the cause should be analyzed, such as excessive welding stress, unqualified welding materials, etc., and corresponding repair measures should be taken, such as re-welding, adjusting welding parameters, etc.

[0068] The welded tower and foundation ring are inspected visually, including welding defects and weld shape defects (such as uneven weld width, excessive or insufficient excess height, etc.). Inspectors conduct inspections in accordance with the Level II standard of XGS07007 "Welding Appearance Quality Inspection Standard", using naked eye observation and measurement with the help of magnifying glasses, weld inspection rulers and other tools.

[0069] Welds that do not meet appearance requirements are recorded and classified. Minor defects can be repaired locally, such as grinding, repair welding, etc.; serious defects require re-evaluation of the welding process and rework of unqualified welds to ensure that the weld appearance meets the requirements.

[0070] RT ray inspection is used to conduct non-destructive testing on the inside of the weld. The ray projection characteristics of the material and the differences in the absorption and attenuation of x-rays by different materials are used to make photos with different blackness of images to observe the internal structure. The inspection standard is based on GB / T19938-2005 / ISO2504:1973.

[0071] Before testing, select appropriate parameters such as radiation source (such as X-ray), film type (such as large copper gong), sensitivity method (such as Pb), tube voltage (240-290KV), tube current (5mA (Ci)), focal length (500mm), exposure time (3-5min) according to the thickness and material of the weld. The developing temperature is controlled at 20°C and the developing time is 6min to ensure that the film blackness is between 2.0-4.0.

[0072] Analyze the test results to determine whether there are defects inside the weld, such as pores, slag inclusions, incomplete penetration, etc. For the defects found, adopt corresponding repair methods according to their location, size and severity, such as patching, re-welding, etc., and then perform RT ray inspection again to ensure that the internal quality of the weld meets the requirements.

[0073] Conduct mechanical property tests such as tensile test, bending test and impact test in accordance with relevant standards (such as GB2651-89 "Welded joint tensile test method", GB2653-89 welded joint bending and flattening test method, GB / T229-2007 metal material Charpy pendulum impact test method, etc.).

[0074] When preparing the tensile test specimen, ensure that the specimen size is accurate and the diameter deviation of the gauge part does not exceed the specified range. Carry out the tensile test on the material testing machine, record the yield strength, tensile strength, elongation and other data, and judge whether the strength of the welded joint meets the requirements. The bending test adopts three-point bending or four-point bending. According to the thickness of the plate, the appropriate bending core diameter and support spacing are selected to observe whether cracks are generated after the specimen is bent, and the plasticity of the welded joint is evaluated. The impact test uses a Charpy pendulum impact tester to prepare V-notch specimens, conduct impact tests at different temperatures, record the impact absorption energy, and evaluate the toughness of the welded joint, especially the low-temperature toughness.

[0075] Metallographic test Metallographic tests were conducted to check the metallographic structures of the weld center, overheating zone, and quenching zone, the dendritic segregation, lamellar segregation, and regional segregation of weld metal, the organizational structure of different organizational characteristic areas, the changes in the organization and properties on both sides of the fusion line of heterogeneous joints, and the ferrite content in the Q345E steel weld. The metallographic structure was observed according to GB / T13298-91 Metal Microstructure Inspection Method.

[0076] When preparing metallographic samples, first cut the samples, and pay attention to avoid overheating and other phenomena that affect the structure. Then perform inlaying, grinding, polishing and other treatments, and use a suitable corrosive agent for corrosion to clearly display the metallographic structure. Observe the metallographic structure under a metallographic microscope, analyze the organizational morphology, grain size, etc., determine whether the welding process is reasonable, whether there are defects such as overheating and overburning, and ensure that the metallographic structure meets the requirements.

Claims

1. A method for welding a tower and a foundation ring of a wind turbine generator set, characterized in that: The following steps are involved: Step 1: Welding preparation stage Q345E steel is selected as the tower base material, and its chemical composition is analyzed to ensure that it meets the corresponding standards, including C content of 0.18%, Mn content of 1.00-1.60%, Si content less than 0.55%, P content less than 0.025%, S content less than 0.025%, V content of 0.02-0.15%, Nb content of 0.015-0.06%, and Ti content of 0.02-0.20%; Welding materials are strictly screened. Arc welding electrodes are E5015-G with a diameter of 3.2mm; CO2 gas shielded welding electrodes are TH550-N with a diameter of 2.0mm; argon-rich mixed gas shielded welding electrodes are ER50-6 with a diameter of 1.2mm. All welding materials are re-inspected by batch before use to ensure that their performance meets the requirements, including yield strength>355MPa, elongation>20%, and the performance of welding and heat-affected areas is not less than 80% of the parent material; Welding equipment debugging: Select appropriate welding equipment and debug the equipment to normal working state to ensure that parameters such as welding current, voltage, gas flow rate, etc. can be stably adjusted; Cut the tower base material, use plasma cutting or oxyacetylene cutting for steel plates, process the cut area and gap after cutting, remove burrs and oxide layers, chamfer the holes, and ensure that the verticality and inclination tolerances of the cut surface meet the requirements; Increase the cutting oxygen purity to above 99.5%, and use liquid oxygen to improve cutting quality and speed; optimize the cutting speed and adjust it according to actual conditions to ensure the cutting effect; Process the steel plate after rolling. When rolling, the direction of the roller should be consistent with the rolling direction of the steel plate. Clean the debris on the surface of the steel plate. Make samples according to the cylinder diagram to avoid mechanical damage. Ensure that the roller is well connected during butt welding. Clean the oxides at the spot welding. The gap between the butt plates is 0.5-2mm. The vertical edge error is not greater than the nominal wall thickness and the maximum is 3mm. After the initial formation of the cylindrical section, spot welding is performed first and then submerged arc welding. After welding, adjust the pipe section and test it with a ruler. Step 2: Welding implementation stage The welding method is determined as follows: argon-rich mixed gas shielded welding is used for welding, wherein the shielding gas is 80% Ar + 20% CO2; the welding current is 220-280A; the welding speed is 300-500mm / min; the gas flow rate is 15-20L / min; Optimization of welding process parameters Energy line selection: Calculate energy line according to the formula q=IU / v, set energy line to 1.71KJ / cm, where welding current I is 220-280A, arc voltage U is 24-30V, welding speed v is 300-500mm / min, to ensure that the tensile strength of the welded joint is high, the softening phenomenon of the heat-affected zone is relatively light, and the microstructure of the weld zone is acicular ferrite, martensite and ferrite; Selection of droplet transfer form: Jet transfer mode is adopted, and the welding process parameters are welding current 120-220A, voltage 17-18V, welding speed 300±50mm / min, gas flow 15-20L / min, to ensure high quality of weld formation and less spatter; Single section longitudinal seam and flange welding Use suspended submerged arc welding to weld a single longitudinal seam, and reserve a 5mm flange to compensate for axial deformation. According to theoretical analysis and experimental measurement, the cylindrical welding volume shrinks by about 7.64mm. The blank body height and flange thickness are adjusted accordingly to reduce material and processing workload and optimize the welding production site. The tailor-welded flange is welded with a partial anti-deformation solution. The first two circles are spot welded first. The arc plate and the welding arc plate are deformed and filled into a group. Then the large arc plates of the adjacent groups are welded and deformed. Finally, two half arc plates are welded into a complete flange. During the welding process, communication is used to further reduce welding deformation, ensure the overall roundness of the flange and make timely adjustments, and optimize the welding production site. Two-section welding Use 20% CO2 + 80% Ar as welding shielding gas, reduce welding voltage to 22-33V to reduce spatter; at the same time, increase the content of Ti, Al and other elements in the welding rod appropriately, or improve the control form of the welding machine, such as using CO2-CO2, PS-CO2 control method, or coat the workpiece surface, choose appropriate powder to prevent spraying, so as to further reduce spatter; The roller frame is assembled into two sections of cylinders through the FUB40 two-section pipe group. Four groups of roller frames are installed on the integral base. The hydraulic cylinder is used to adjust the butt clearance and misalignment. The active roller frame is driven by an AC motor through a reducer. It runs smoothly, has high efficiency, and has a large transmission torque. The inverter is used for speed regulation. The roller frame is annealed and sandblasted after welding. The special tooling platform for two-section assembly is optimized to improve welding efficiency and reduce the workload of workers. Large section butt welding and inner circumferential seam welding A 40-ton hydraulic group roller frame + an 80-ton adjustable walking roller frame are used to assemble and lengthen the large sections of the cylinder. A 1250A submerged arc welding trolley is used for inner girth welding. The welded joints are optimized and the weld surface is changed to a convex shape to offset some tensile stress and reduce the occurrence of thermal cracks. Consider replacing the original acidic electrodes with more desulfurized alkaline electrodes A307 and A107, both of which have chemical compositions consistent with DC reverse phase; Outer seam welding Double-sided double-arc welding is used to weld some welds that need to be cleaned and welded through. The equipment consists of CZ22-6x5 welding manipulator, 1250A suspended submerged arc welding system, 80-ton adjustable walking roller frame, etc. It is used for welding the outer ring seam after the long-length assembly of large sections of the cylinder. The production line equipment is reasonably planned, and the work site is ready before the assembly is completed; The non-grooved overlap form is used instead of the 16x45° grooved connection form on the cylinder round gasket to improve the heat input and sedimentation rate of the unit. The double arc gas protection is used to avoid the post-welding cleaning process, simplify the welding process, and reduce the occurrence of inclusions. Step 3: Welding quality control stage Process monitoring and adjustment During the entire welding process, the welding parameters are strictly controlled to ensure that the welding process is smooth and carried out in a straight line. The welding speed is controlled within the preset range and the deposition ratio is controlled between 1.3-1.

5. Strengthen slag removal work, especially on the surface of butt weld layer, to control inclusion defects and ensure welding quality; Post-weld inspection and treatment Carry out visual inspection on the welded tower and foundation ring, including welding defects and weld shape defects; RT ray inspection is used to conduct nondestructive testing on the inside of the weld. By utilizing the ray projection characteristics of the material and the differences in the absorption and attenuation of x-rays by different materials, the photos are made into different blackness of the images to observe the internal structure; Conduct mechanical property tests on welded joints, including tensile test, bending test, and impact test, to ensure that the mechanical properties of welded joints meet the requirements; Metallographic tests were carried out to examine the metallographic structures of the weld center, overheating zone, and quenching zone, the dendritic segregation, lamellar segregation, and regional segregation of weld metal, the organizational structure of areas with different organizational characteristics, the changes in the organization and properties on both sides of the fusion line of dissimilar joints, and the ferrite content in Q345E steel welds.

2. The method for welding the tower and foundation ring of a wind turbine generator set according to claim 1, characterized in that: During the welding preparation stage, when pre-treating the Q345E steel base material, if the steel plate has overall edge bending and local lifting deformation during transportation, storage, cooling, and rolling that affects the cutting quality, the steel plate needs to be corrected before cutting to ensure that the steel plate is in a flat state during cutting, so as to improve the cutting accuracy and ensure the smooth progress of the subsequent welding process.

3. The method for welding a tower and a foundation ring of a wind turbine generator set according to claim 1, characterized in that: During the welding implementation stage, when using argon-rich mixed gas shielded welding, the welding area needs to be cleaned before welding to remove oil, rust and impurities to prevent impurities from entering the weld during the welding process and affecting the weld quality, ensuring that the performance of the welded joint meets the requirements.

4. The method for welding a tower and a foundation ring of a wind turbine generator set according to claim 1, characterized in that: During the welding process of single-section longitudinal seams and flanges, for the suspended submerged arc welding equipment, the parameters of the welding operator, suspended submerged arc welding system, manual machine-adjustable roller frame, and inclined roller frame equipment need to be precisely adjusted according to the specific size of the tower and welding requirements to ensure a stable welding process, good weld formation, and improved welding quality and production efficiency.

5. The method for welding a tower and a foundation ring of a wind turbine generator set according to claim 1, characterized in that: During the two-section assembly welding process, the hydraulic cylinder of the FUB40 two-section pipe assembly roller frame must operate according to a precise control procedure when adjusting the butt clearance and misalignment between the two cylinders to ensure that the butt clearance is controlled within the range of 0.5 - 2mm and the misalignment does not exceed the specified value, thereby ensuring assembly accuracy and improving welding quality.

6. The method for welding a tower and a foundation ring of a wind turbine generator set according to claim 1, characterized in that: During the long-section assembly and inner girth welding process, the 40-ton hydraulic assembly roller frame and the 80-ton adjustable walking roller frame must use a high-precision positioning system when moving and positioning the cylinder to ensure that the cylinder docking position is accurate and the deviation does not exceed the allowable range, providing good conditions for the inner girth welding and ensuring the welding quality.

7. The method for welding a tower and a foundation ring of a wind turbine generator set according to claim 1, characterized in that: During the welding quality control stage, if defects are found inside the weld during the RT ray inspection, appropriate repair measures must be taken according to the type and severity of the defects. For example, small porosity defects can be repaired by repair welding and re-inspected to ensure that the internal quality of the weld meets the requirements.

8. The method for welding a tower and a foundation ring of a wind turbine generator set according to claim 1, characterized in that: During the mechanical properties test, the preparation of specimens for tensile tests, bending tests and impact tests must be carried out in strict accordance with standard specifications to ensure that the specimen size is accurate and the surface is smooth. During the test, test equipment with accuracy that meets the requirements must be used and accurate data must be recorded to ensure the reliability of the test results and accurately evaluate the mechanical properties of the welded joints.

9. The method for welding a tower and foundation ring of a wind turbine generator set according to claim 1, characterized in that: During the production practice and optimization stage, when tracking the production process simultaneously, it is necessary to establish a detailed welding quality record file to record the various parameters, test results, problems encountered and solutions during the welding process, so as to conduct systematic analysis and continuous optimization of the welding process and improve the overall welding quality and production efficiency.

10. The method for welding a tower and foundation ring of a wind turbine generator set according to claim 1, characterized in that: During the entire welding process, the welding environment temperature and humidity need to be monitored and controlled. When the ambient temperature is lower than 5°C, appropriate preheating measures must be taken to ensure that the temperature of the welding area meets the requirements; when the humidity exceeds 90%, dehumidification measures must be taken to prevent porosity defects in the weld and ensure stable welding quality.

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