Hybrid welding process for wind power tower drum

Abstract

The invention discloses a hybrid welding process for a wind power tower drum, which relates to the technical field of wind power tower drum welding and comprises a pretreatment stage, a root filling stage, a single-wire submerged arc filling stage and a one-time filling welding stage for the inner side and the outer side of a drum body, according to the process, solid gas shielded welding, single-wire submerged-arc automatic welding and double-wire submerged-arc automatic welding are combined, carbon arc air gouging back gouging is not needed, procedures are reduced, the cost of auxiliary consumables, personnel, power energy and the like is reduced, carbon gouging and polishing are reduced in the welding process, the workshop smoke dust concentration is reduced by 50% or above, and the welding quality is improved. The arc light radiation is weakened by more than 30%, noise pollution of more than 85 dB generated by carbon arc air gouging is eliminated, the working environment of workers is improved, meanwhile, groove abnormity and weld joint repair caused by carbon arc air gouging back gouging are reduced, and the first-pass yield of weld joints is increased to more than 95%.

Description

Technical Field

[0001] The present invention relates to the technical field of wind power tower welding, and in particular to a hybrid welding process for wind power towers. Background Art

[0002] In the welding operations of the wind turbine tower industry, the conventional submerged arc automatic welding process generally adopts double-sided welding. The operation process of this process is: first weld on one side, then use carbon arc gouging to clean the root on the other side, and then perform grinding after completing the root cleaning. Finally, the filling cover welding work is carried out. This double-sided welding process is a relatively common technical means in the manufacturing process of wind turbine towers, and provides a certain basic method for the welding of wind turbine towers.

[0003] However, this traditional welding process has many obvious shortcomings. The carbon arc gouging root cleaning process directly leads to an increase in process steps. In this process, not only additional auxiliary consumables are required, but also labor costs and power energy consumption are increased. At the same time, carbon arc gouging will generate a large amount of noise and chemical dust, which will sharply deteriorate the working environment of workers and pose a great threat to their health. Moreover, during the carbon arc gouging root cleaning process, abnormal conditions may occur in the groove, which easily leads to the need for weld repair, further increasing production costs and time costs, and affecting production efficiency and product quality. Summary of the Invention

[0004] Based on this, the purpose of the present invention is to provide a hybrid welding process for wind turbine towers to solve the technical problems in the above-mentioned background technology.

[0005] To achieve the above-mentioned object, the present invention provides the following technical solution: a hybrid welding process for wind turbine towers, comprising the following process steps:

[0006] Pretreatment stage: Clean the surface of the wind turbine tower to be welded, remove impurities such as oil, rust, etc., and ensure that the surface roughness Ra is ≤ 25μm;

[0007] Root filling stage: solid wire gas shielded welding process is used to fill the root inside the cylinder. The welding current is controlled to 250-350A, the welding voltage is 28-32V, and the welding speed is 30-40cm / min. A weld layer with a thickness of 3-4mm and uniform back surface is formed. The solid wire gas shielded welding process is equipped with arc starting and arc ending plates at the starting and ending positions of the welding. The arc starting and arc ending time is controlled to 3-5 seconds.

[0008] The solid wire gas shielded welding in the root filling stage adopts argon-rich mixed gas protection, the gas composition is 80% Ar + 20% CO2, the gas flow rate is 15-25L / min, and single-sided welding and double-sided forming are achieved without backing;

[0009] Single-wire submerged arc filling stage: Use single-wire submerged arc automatic welding equipment to perform filling welding on the inner and outer sides of the cylinder. When welding the inner side, the welding current is 500-600A, the voltage is 30-34V, and the speed is 45-55cm / min. The welding parameters for the outer side are the same as those for the inner side. An automatic flux recovery device is equipped during the welding process, and the flux recovery rate is not less than 90%;

[0010] A temperature maintenance process is set between the single-wire submerged arc filling stage and the double-wire submerged arc welding stage. The electric heating plate is used to maintain the preheating temperature of the weld area at 60-80°C to avoid the occurrence of cold cracks in the welding;

[0011] Double-wire submerged arc welding stage: Double-wire submerged arc automatic welding is first performed on the outside of the cylinder, with the leading wire welding current of 600-700A, the trailing wire current of 550-650A, the voltage of 32-36V, and the speed of 50-60cm / min. The distance between the two wires is controlled at 15-25mm. After the outer weld is completed, double-wire submerged arc welding with the same parameters is performed on the inside of the cylinder. The welding power supply of the double-wire submerged arc automatic welding adopts pulse welding mode, and the molten pool is precisely controlled by dynamic adjustment of the pulse frequency of 50-100Hz and the duty cycle of 30%-70%;

[0012] In the twin-wire submerged arc welding stage, the leading wire and the trailing wire use different polarity configurations. The leading wire is connected to DC positively and the trailing wire is connected to DC negatively. This reduces weld porosity defects through the synergistic effect of the arc electric field.

[0013] Inspection and acceptance stage: After welding is completed, 100% MT inspection and 100% UT inspection are carried out in sequence. MT inspection uses magnetic particle inspection equipment that complies with the JB / T6061 standard, and UT inspection uses ultrasonic flaw detectors that comply with the JB / T4730.3 standard.

[0014] During the inspection and acceptance phase, UT testing uses phased array ultrasonic testing technology, which enables quantitative analysis of defects across the entire weld cross section through multi-probe array scanning. The detection sensitivity is 15dB higher than that of traditional UT.

[0015] The order of implementation of each process step is:

[0016] Pretreatment, solid wire gas shielded welding for weld pass 1, single wire submerged arc internal and external filling for weld pass 2, temperature maintenance, outer twin wire submerged arc welding for weld pass 3, inner twin wire submerged arc welding for weld pass 3, MT testing, UT testing;

[0017] By collaboratively optimizing welding parameters, the process improves the deposition efficiency of wind turbine tower girth welding by more than 40% compared to traditional double-sided submerged arc welding, reduces the amount of filler metal per unit weld length by 20%-30%, and eliminates the need for carbon arc gouging and root cleaning.

[0018] The process combines pulsed twin-wire submerged arc welding technology with a temperature maintenance process to control the welding deformation of wind turbine towers to within 0.5mm / m, increase the first-pass weld pass rate to over 95%, and reduce labor hours by 10-15 hours per tower compared to traditional processes.

[0019] The process uses a carbon-free root-cleaning welding process design to reduce the welding fume concentration in the workshop by more than 50% and the arc radiation intensity by more than 30%, while eliminating the noise pollution of more than 85dB generated by carbon arc gouging.

[0020] In summary, the present invention mainly has the following beneficial effects: the present invention adopts a combination of solid gas shielded welding, single-wire submerged arc automatic welding and double-wire submerged arc automatic welding through this process, and there is no need for carbon arc gouging to clean the root, which reduces the process and reduces the costs of auxiliary consumables, personnel and power energy. During the welding process, carbon gouging and grinding are reduced, the smoke concentration in the workshop is reduced by more than 50%, the arc radiation is weakened by more than 30%, the noise pollution of more than 85dB generated by carbon arc gouging is eliminated, and the working environment of workers is improved. At the same time, the process also reduces the groove abnormalities and weld rework caused by carbon arc gouging to clean the root, and increases the weld pass rate to more than 95%. By optimizing the welding parameters, the deposition efficiency is increased by more than 40%, the welding deformation is controlled within 0.5mm / m, the amount of welding filler metal is reduced, labor hours are saved, and production efficiency and product quality are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the hybrid welding process of the present invention. DETAILED DESCRIPTION

[0022] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be understood as limiting the present invention.

[0023] The following describes an embodiment of the present invention based on its overall structure.

[0024] Example 1

[0025] like Figure 1 As shown, this embodiment takes the circumferential seam welding of a 1.5MW wind turbine tower as an application scenario, and describes in detail the full process of the hybrid welding process, including pretreatment, root filling, single-wire submerged arc filling, double-wire submerged arc welding, and inspection and acceptance steps;

[0026] Preprocessing stage

[0027] Surface cleaning and roughness control: Grinding with a grinding wheel removes oil, rust, and scale from the surface to be welded, reducing the roughness to Ra ≤ 25μm. This provides a clean, rough interface for subsequent welding, increases the mechanical bond between the solder and the base material, and avoids defects such as pores and lack of fusion caused by surface impurities. Sampling tests with a roughness tester show that the surface roughness is uniform and controllable, slag falls off smoothly during welding, and the bonding strength between the root filler weld and the base material is increased by 15%, laying the foundation for subsequent welding quality.

[0028] Root filling stage (solid wire gas shielded welding)

[0029] Single-sided welding and double-sided forming basis: Using 80% Ar + 20% CO2 argon-rich gas protection, combined with precise current and voltage control (300A / 30V), a 3-4mm thick root weld layer is formed on the inner side of the cylinder, achieving uniform back-side forming without a backing, replacing the back-side root cleaning process of the traditional process. The back-side weld bead has a uniform excess height (1.2-1.5mm). UT spot checks show no root incomplete penetration, and the single-sided welding and double-sided forming pass rate reaches 98%. Compared with the traditional process, the root cleaning process is reduced, saving 4 hours of work time for a single tower.

[0030] Arc starting plate and arc ending plate setting: Install arc starting plate and arc ending plate at the starting and ending positions of welding to avoid arc crater cracks, lack of fusion and other defects at the starting and ending points of the arc, and ensure that the quality of the weld at the beginning and end is consistent with that in the middle section;

[0031] Single-filament submerged arc filling stage

[0032] Efficient filling and penetration control: Using 550A high current single-wire submerged arc welding, the inside and outside of the cylinder are filled once, taking advantage of the arc thermal efficiency under flux coverage to quickly increase the weld thickness. At the same time, the metallurgical reaction of the flux purifies the molten pool and reduces defects such as pores and slag inclusions.

[0033] Flux recovery system: equipped with automatic flux recovery device (recovery rate ≥ 90%) to reduce flux waste, lower production costs, and avoid welding parameter fluctuations caused by flux accumulation;

[0034] The single-pass filling deposition efficiency reaches 120g / m, which is three times higher than that of traditional manual welding. The weld surface is smooth and defect-free, and the slag stripping property is good, providing a flat base for subsequent double-wire submerged arc welding.

[0035] Temperature maintenance process

[0036] Preheating and interpass temperature control: The ceramic electric heating plate is used to maintain the weld area at 60-80°C, reducing welding thermal stress, slowing down the cooling rate, avoiding the formation of martensite structure, preventing the occurrence of welding cold cracks, and improving the fluidity of the molten pool and enhancing the toughness of the weld metal;

[0037] The temperature difference in the weld area is ≤10°C. After hardness testing (HV10), the hardness of the heat-affected zone is ≤250HV, which is 20% lower than that of the non-preheating process. The cold crack incidence rate is reduced to 0, meeting the fatigue strength requirements of the wind turbine tower.

[0038] Double wire submerged arc welding stage

[0039] Dual-wire collaborative molten pool control: The leading wire (DC positive connection, 650A) forms a deep molten pool, while the trailing wire (DC reverse connection, 600A) fills the metal. The two wires are spaced 20mm apart. The synergistic effect of the arc electric field reduces porosity defects. At the same time, the pulse welding mode (80Hz / 50% duty cycle) dynamically controls the molten pool solidification process and refines the grain size.

[0040] Polarity configuration optimization: DC positive connection of the leading wire increases penetration depth, while DC reverse connection of the trailing wire increases penetration width, forming a "deep weld pool + wide fill" weld bead shape, which meets the requirements of tower thick plate welding and reduces delamination defects;

[0041] The deposition efficiency is 40% higher than that of single-wire submerged arc welding, the single-pass welding speed is 55cm / min, the weld bead is fully formed (reinforced height is 2-3mm), and UT testing shows that the defect rate of porosity, slag inclusion, etc. is 70% lower than that of traditional submerged arc welding. The impact toughness of the weld metal (-20℃) is ≥34J, meeting the requirements of DNV-GL standards.

[0042] Testing and acceptance stage

[0043] MT magnetic particle testing: uses a continuous method to detect weld surface and near-surface defects (such as cracks and lack of fusion), with a sensitivity reaching the A1-30 / 100 test piece standard, ensuring that the surface quality of weld joints meets the requirements of JB / T6061-2007 Level I.

[0044] Phased array UT testing: Multi-probe array scanning enables quantitative analysis of defects across the entire weld cross-section. Its detection sensitivity is 15dB higher than that of traditional UT, and it can identify tiny defects ≤1mm, meeting the high reliability requirements for safe service of wind turbine towers.

[0045] 100% MT and UT inspections achieve a first-pass pass rate of 96%, an 11% improvement over traditional processes. Defect location accuracy is ≤ 1mm, eliminating safety hazards to tower operation caused by missed inspections and providing quality assurance for subsequent installation and maintenance.

[0046] This process, through parameter coordination and technological innovation in each process, not only improves welding efficiency and reduces costs, but also significantly improves weld quality and working environment, meeting the welding requirements of large thickness and high reliability of wind turbine towers.

[0047] Although an embodiment of the present invention has been shown and described, this specific embodiment is merely an explanation of the present invention and is not a limitation of the invention. The specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments or examples. After reading this specification, those skilled in the art may make modifications, substitutions and variations to the embodiment without creative contribution as needed without departing from the principles and purpose of the present invention. However, as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A hybrid welding process for wind turbine towers, characterized in that: The process steps include: Pretreatment stage: Clean the surface of the wind turbine tower to be welded, remove impurities such as oil, rust, etc., and ensure that the surface roughness Ra is ≤ 25μm; Root filling stage: solid wire gas shielded welding process is used to fill the root inside the cylinder. The welding current is controlled to 250-350A, the welding voltage is 28-32V, and the welding speed is 30-40cm / min. A weld layer with a thickness of 3-4mm and uniform back surface is formed. The solid wire gas shielded welding process is equipped with arc starting and arc ending plates at the starting and ending positions of the welding. The arc starting and arc ending time is controlled to 3-5 seconds. Single-wire submerged arc filling stage: Use single-wire submerged arc automatic welding equipment to perform filling welding on the inner and outer sides of the cylinder. When welding the inner side, the welding current is 500-600A, the voltage is 30-34V, and the speed is 45-55cm / min. The welding parameters for the outer side are the same as those for the inner side. An automatic flux recovery device is equipped during the welding process, and the flux recovery rate is not less than 90%; Double-wire submerged arc welding stage: Double-wire submerged arc automatic welding is first performed on the outer side of the cylinder, with the leading wire welding current of 600-700A, the trailing wire current of 550-650A, the voltage of 32-36V, the speed of 50-60cm / min, and the double-wire spacing controlled at 15-25mm. After the outer weld is completed, double-wire submerged arc welding with the same parameters is performed on the inner side of the cylinder. The double-wire submerged arc automatic welding power supply adopts pulse welding mode, and the molten pool is precisely controlled by dynamic adjustment of the pulse frequency of 50-100Hz and the duty cycle of 30%-70%; Inspection and acceptance stage: After welding is completed, 100% MT inspection and 100% UT inspection are carried out in sequence. MT inspection uses magnetic particle inspection equipment that complies with the JB / T6061 standard, and UT inspection uses ultrasonic flaw detectors that comply with the JB / T4730.3 standard.

2. The hybrid welding process for wind turbine tower according to claim 1, characterized in that: The solid wire gas shielded welding in the root filling stage adopts argon-rich mixed gas protection, the gas composition is 80% Ar+20% CO2, the gas flow rate is 15-25L / min, and single-sided welding and double-sided forming are achieved without a backing.

3. The hybrid welding process for wind turbine tower according to claim 1, characterized in that: A temperature maintaining process is provided between the single-wire submerged arc filling stage and the double-wire submerged arc welding stage, and the weld area is kept at a preheating temperature of 60-80° C. by an electric heating plate to avoid the generation of welding cold cracks.

4. The hybrid welding process for wind turbine tower according to claim 1, characterized in that: The leading welding wire and the trailing welding wire in the double-wire submerged arc welding stage adopt different polarity configurations, the leading welding wire is directly connected to DC, and the trailing welding wire is reversely connected to DC, so as to reduce weld porosity defects through the synergistic effect of the arc electric field.

5. The hybrid welding process for wind turbine tower according to claim 1, characterized in that: During the inspection and acceptance stage, UT inspection uses phased array ultrasonic testing technology, and quantitative analysis of defects in the entire cross-section of the weld is achieved through multi-probe array scanning. The detection sensitivity is improved by 15dB compared with traditional UT.

6. The hybrid welding process for wind turbine tower according to any one of claims 1 to 5, characterized in that: The implementation order of each process step is: Pretreatment, weld pass 1 solid wire gas shielded welding, weld pass 2 single wire submerged arc inner and outer filling, temperature maintenance, weld pass 3 outer twin wire submerged arc welding, weld pass 3 inner twin wire submerged arc welding, MT testing, UT testing.

7. The hybrid welding process for wind turbine tower according to claim 1, characterized in that: By co-optimizing welding parameters, the process improves the deposition efficiency of wind turbine tower girth welding by more than 40% compared with traditional double-sided submerged arc welding, reduces the amount of filler metal used per unit length of weld by 20%-30%, and eliminates the need for carbon arc gouging and root cleaning.

8. The hybrid welding process for wind turbine tower according to claim 1, characterized in that: The process combines pulsed twin-wire submerged arc welding technology with a temperature maintenance process to control the welding deformation of wind turbine towers within 0.5mm / m, increase the first-time pass rate of welds to over 95%, and reduce labor hours by 10-15 hours per tower compared to traditional processes.

9. The hybrid welding process for wind turbine tower according to claim 1, characterized in that: The process is designed to reduce the welding fume concentration in the workshop by more than 50% and the arc radiation intensity by more than 30% through the welding process design of carbon-free gouging and root cleaning, while eliminating the noise pollution of more than 85dB generated by carbon arc gouging.

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