Welding method for offshore wind power large and thick steel plate cylinder

Abstract

The invention relates to the technical field of offshore wind power generation pipe pile manufacturing, in particular to a welding method of an offshore wind power large and thick steel plate barrel, which comprises the steps of beveling, barrel rolling, preheating, positioned welding, backing welding, inner groove welding, carbon arc air gouging back gouging and outer groove welding. Flame cutting is matched with mechanical milling to manufacture a semi-narrow gap groove, the sectional area of the groove is improved, the semi-narrow gap submerged arc automatic welding process is achieved, and the welding efficiency is improved. Due to the V + U-shaped design of the inner groove, the good fusion ratio of the root is guaranteed, and the defects of incomplete penetration and hot cracks of the root are reduced; and the back gouging depth of an outer side welding seam is reduced, the labor intensity of an operator is reduced, the mechanization degree is improved, carbonization of a base metal groove is reduced, and the internal welding quality is improved. The V + U-shaped groove form is easy to weld, the groove is regular, and the appearance is attractive; compared with a traditional V-shaped groove, the angle of the V + U-shaped groove is smaller, the filling amount of welding materials is reduced, and the production cost is saved.

Description

Technical Field

[0001] The invention relates to the technical field of offshore wind power generation pipe pile manufacturing, and in particular to a welding method for an offshore wind power generation thick steel plate cylinder. Background Art

[0002] Offshore monopiles are important basic structural parts for supporting wind turbine towers. The design diameter of the offshore monopiles is large, which is currently more than 11 meters. The steel plate thickness is 115mm, and the tonnage of the single barrel section is large. The welding process mainly affects the production efficiency of the product. The joint seams and longitudinal seams in the welding production process have a long welding cycle due to the geometric increase in the cross-sectional area of ​​the weld due to the plate thickness and the long circumferential weld caused by the large diameter. The traditional welding groove form is an X-shaped groove with a groove angle of 45 to 60°. After welding one side, the other side is carbon arc gouging and root cleaning is performed, and the slag, oxide scale and other impurities of the carbon arc gouging are polished to remove them, and then submerged arc welding is performed. This type of groove welding is widely used in the manufacture of wind turbine pipe piles.

[0003] When welding thick plates with X-shaped grooves, the groove depth and cross-sectional area will increase as the plate thickness increases, resulting in an increase in the amount of welding material filled and a long welding cycle. In terms of welding quality, the root of the thick plate X-shaped groove is too narrow, and the poor penetration rate is prone to thermal cracking, which makes the back root cleaning deeper, increasing the consumption of raw materials for carbon arc gouging, the consumption of grinding wheels and labor costs. The consumption of welding materials increases, the welding cycle is extended, and the labor consumption of workers is high. The groove after manual carbon arc gouging is irregular, which is prone to welding defects and the weld is not beautiful. It is impossible to reduce the welding time and improve welding efficiency to reduce costs.

[0004] After searching, the Chinese patent publication number is CN103286528B, which discloses a thick-walled cylinder longitudinal seam narrow gap welding groove processing technology. The Chinese patent publication number is CN105234535B, which discloses a cylinder welding process. The above-mentioned prior arts all disclose U+V-shaped groove design. After investigation and research, in the process of application, the equipment for processing U-shaped groove is not enough to meet the production needs, the equipment investment is high, the processing efficiency is low, and the practicality is not strong. Especially for steel plates with a thickness of more than 100mm, the expected benefits cannot be obtained. For thick steel plates, during the welding process, the welding quality of the root of the groove cannot be guaranteed because the groove depth is too deep.

[0005] The present invention takes into account the relationship between input and efficiency, adopts flame cutting in combination with mechanical milling to produce a semi-narrow gap groove, improves the cross-sectional area of ​​the groove, and combines the efficient welding process of thick steel plates to improve efficiency and welding quality. Summary of the invention

[0006] The purpose of the present invention is to solve the problems of high equipment investment, low processing efficiency, poor practicality, and inability to ensure welding quality in the above-mentioned prior art, and to provide a welding method for large thick steel plate cylinders of offshore wind power plants, which can realize semi-narrow gap submerged arc welding, reduce the amount of welding materials, improve production efficiency, reduce labor intensity, improve welding quality, and save production costs.

[0007] To achieve the above object, the technical solution of the present invention is: a welding method for a thick steel plate cylinder of an offshore wind power plant, comprising the following steps:

[0008] S1. Beveling: flame cutting is used to bevel the inner and outer sides of the welds at both ends of the steel plate. A flame is used to pre-open a small-angle X-shaped bevel. The inner bevel is a one-way bevel with an angle of β, β is 14°-16°, and the outer bevel is a one-way bevel with an angle of γ, γ is 30°-40°. The thickness of the cylinder plate is T, the depth T1 of the outer bevel is 14-16mm, the thickness of the blunt edge X between the inner and outer bevels is 2mm, and the depth T2 of the inner bevel is T-T1-X. Then a self-propelled U-shaped beveling machine is used to mechanically mill the cut inner bevel root into a U-shaped bevel. The opening angle of the U-shaped bevel is 13°-18°, and the root of the U-shaped bevel is a fillet with a radius R of 6-10mm.

[0009] S2. Rolling the cylinder: Roll the steel plate with grooved edges according to the diameter of the cylinder. The cylinder formed after rolling has no gaps at the joints, and the inner groove forms a V+U-shaped semi-narrow gap groove, and the outer groove forms a V-shaped groove;

[0010] S3, preheating: preheat the groove and surrounding parent materials;

[0011] S4, positioning welding: positioning welding is performed by using metal-metal gas shielded welding at the blunt edge of the inner side of the formed cylinder;

[0012] S5. Base welding: Base welding is performed by using metal-metal arc welding at the outer groove of the longitudinal or annular gap of the cylinder that has completed positioning welding;

[0013] S6. Inner groove welding: For the longitudinal inner weld of the cylinder that has completed the base welding, single-wire submerged arc or double-wire submerged arc automatic welding is used for full welding. The inner seam of the circumferential weld can be welded synchronously by multiple single-wire submerged arc automatic welding machines.

[0014] S7, Carbon arc gouging and root cleaning: Carbon arc gouging and root cleaning is performed on the outer weld of the cylinder that has completed the inner groove welding;

[0015] S8. External groove welding: Double-wire submerged arc or single-wire submerged arc automatic welding is used to fully weld the external groove of the cylinder after root cleaning.

[0016] The preferred technical solution is that the angle β of the inner groove is 15°, the angle γ of the outer groove is 35°, the thickness T of the cylinder plate is 100 mm, the depth T1 of the outer groove is 15 mm, the thickness of the blunt edge X between the inner groove and the outer groove is 2 mm, the depth T2 of the inner groove is T-T1-X=83 mm, the opening angle of the U-shaped groove is 16°, and the radius R of the fillet is 8 mm.

[0017] The preferred technical solution is that after the cylinder is rolled, a 30°V+16°U-shaped semi-narrow gap groove is formed at the inner groove, and a V-shaped groove with an angle of 70° is formed at the outer groove.

[0018] The preferred technical solution is that the preheating temperature is 20°C-120°C. When measuring the preheating temperature, steel plates ≥50mm should be measured at a distance of 75mm from the weld.

[0019] The preferred technical solution is that the welding filling thickness during the base welding is 7mm-8mm.

[0020] The preferred technical solution is that when the carbon arc air planer is used to clean the root, the outer groove is carbon planed to form a second U-shaped groove, the angle of the second U-shaped groove is greater than 16°, and the radius of the fillet should be ≥5mm.

[0021] The preferred technical solution is that during positioning welding and backing welding, the diameter of the welding wire for metal arc welding is 1.2 mm, the shielding gas used is 100% CO2, the welding current is 180A-280A, the welding voltage is 25V-32V, the welding speed is 150mm / min-320mm / min, and the gas flow rate during welding is 18L / min-25L / min.

[0022] The preferred technical solution is that during inner groove welding and outer groove welding, the wire diameter of single-wire submerged arc welding is 4.0 mm, the flux is dried for 1 hour before use, the drying temperature is 300°C-350°C, the front wire current during welding is 500A-760A, the front wire voltage during welding is 26V-34V, and the welding speed is 390mm / mim-440mm / min.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. There is no need to make major changes to the original production process of the workshop. By combining flame cutting with mechanical milling, the cross-sectional area of ​​the thick plate groove is changed, the amount of welding raw materials is reduced, the welding time is reduced, and the welding efficiency is improved.

[0025] 2. The inner V+U groove can ensure the root penetration without generating thermal cracks; it reduces the root cleaning depth at the outer groove, reduces the labor intensity of the operator, improves the degree of mechanization, reduces the carbonization of the parent material groove, and improves the internal welding quality.

[0026] 3. The V+U-shaped groove is easy to weld, with regular groove and beautiful appearance. The V+U-shaped groove has a smaller angle than the traditional V-shaped groove, which reduces the filling amount of welding materials and saves production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 : A schematic diagram of the structure of the inner bevel and the outer bevel after flame cutting of the present invention;

[0028] Figure 2 : A schematic diagram of the structure of the inner groove and the outer groove after mechanical milling of the present invention;

[0029] Figure 3 : A schematic diagram of the structure of the inner groove and the outer groove after flame cutting in Example 1 of the present invention;

[0030] Figure 4 : A schematic diagram of the structure of the inner groove and the outer groove after mechanical milling in Example 1 of the present invention;

[0031] Figure 5 : A schematic diagram of the structure of the original groove in the prior art with disadvantages;

[0032] Figure 6 : A structural diagram of the root cleaning depth of carbon arc air planing in the prior art;

[0033] Figure 7 : A schematic diagram of the structure after the root cleaning at the outer groove in the prior art;

[0034] Figure 8 : A schematic diagram of the structure after the outer groove is cleaned;

[0035] Fig. 9 : Schematic diagram of the front weld area in the prior art;

[0036] Fig.10 : Schematic diagram of the back weld area in the prior art;

[0037] Fig.11 : Schematic diagram of the front weld area in the present invention;

[0038] Fig.12 : Schematic diagram of the back weld area in the present invention; DETAILED DESCRIPTION

[0039] The specific implementation of the present invention is further described below in conjunction with the examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention, and cannot be used to limit the protection scope of the present invention.

[0040] like Figure 1-12 As shown, a welding method for a thick steel plate cylinder of an offshore wind power plant comprises the following steps:

[0041] S1, beveling: Figure 1 and 2 As shown, flame cutting is used to open grooves on the inner and outer sides of the welding parts at both ends of the steel plate, and flame is used to pre-open a small angle X-shaped groove. The inner groove is a one-way groove with an angle of β, β is 14°-16°, and the outer groove is a one-way groove with an angle of γ, γ is 30°-40°. The thickness of the cylinder plate is T, the depth T1 of the outer groove is 14-16mm, the thickness of the blunt edge X between the inner groove and the outer groove is 2mm, and the depth T2 of the inner groove is T-T1-X. Then, a self-propelled U-shaped groove machine is used to mechanically mill the root of the cut inner groove into a U-shaped groove. The opening angle of the U-shaped groove is 13°-18°, and the root of the U-shaped groove is a fillet with a radius R of 6-10mm.

[0042] S2. Rolling the cylinder: Roll the steel plate with grooved edges according to the diameter of the cylinder. The cylinder formed after rolling has no gaps at the joints, and the inner groove forms a V+U-shaped semi-narrow gap groove, and the outer groove forms a V-shaped groove;

[0043] S3. Preheating: Preheat the groove and surrounding parent materials; the preheating temperature is 20℃-120℃. When measuring the preheating temperature, steel plates ≥50mm should be measured at a distance of 75mm from the weld.

[0044] S4, positioning welding: positioning welding is performed by using metal-metal gas shielded welding at the blunt edge of the inner side of the formed cylinder;

[0045] S5. Base welding: Use gas metal arc welding to perform base welding on the outer groove of the longitudinal or annular gap of the cylinder that has completed positioning welding. The welding filling thickness is 7mm-8mm.

[0046] S6. Inner groove welding: For the longitudinal inner weld of the cylinder that has completed the base welding, single-wire submerged arc or double-wire submerged arc automatic welding is used for full welding. The inner seam of the circumferential weld can be welded synchronously by multiple single-wire submerged arc automatic welding machines.

[0047] S7. Carbon arc gouging and root cleaning: Carbon arc gouging and root cleaning are performed on the outer weld of the cylinder that has completed the inner groove welding. Since the inner groove is designed in V+U shape, the disadvantage of poor root penetration is eliminated, and the root cleaning depth of the outer weld is reduced, the carbon rod consumption and the metal gouging amount are reduced. The outer groove is carbon gouged to form a No. 2 U-shaped groove. The angle of the No. 2 U-shaped groove is greater than 16°, and the radius of the fillet should be ≥5mm.

[0048] S8. External groove welding: Double-wire submerged arc or single-wire submerged arc automatic welding is used to fully weld the external groove of the cylinder after root cleaning.

[0049] During positioning welding and backing welding, the welding wire for metal electrode gas shielded welding is Jinglei flux-cored wire GFL-71Ni, the welding wire diameter is 1.2mm, the shielding gas used is 100% CO2, the welding current is 180A-280A, the welding voltage is 25V-32V, the welding speed is 150mm / min-320mm / min, and the gas flow rate during welding is 18L / min-25L / min.

[0050] When welding inner groove and outer groove, the welding wire for single-wire submerged arc welding is H-14, the welding wire diameter is 4.0mm, the flux used during welding is superflux 55ULT, and the flux is dried for 1 hour before use. The drying temperature is 300℃-350℃, the front wire current during welding is 500A-760A, the front wire voltage during welding is 26V-34V, and the welding speed is 390mm / mim-440mm / min.

[0051] like Figure 3 and 4 In the embodiment 1 shown, the angle β of the inner groove is 15°, the angle γ of the outer groove is 35°, the thickness T of the cylinder plate is 100 mm, the depth T1 of the outer groove is 15 mm, the thickness X of the blunt edge between the inner groove and the outer groove is 2 mm, the depth T2 of the inner groove is T-T1-X=83 mm, the opening angle of the U-shaped groove is 16°, and the radius R of the fillet is 8 mm. When the root of the inner groove is processed into a U-shaped groove by mechanical milling, the processing angle α is 8°. After the cylinder is rolled, a 30°V+16°U-shaped semi-narrow gap groove is formed at the inner groove, and a V-shaped groove with an angle of 70° is formed at the outer groove.

[0052] like Figure 5 As shown, in the prior art, the original welding groove of the thick plate cylinder is an X-shaped groove, the inner groove angle is 45°, and the outer groove angle is 70°. Figure 5 The arc cannot reach the A area, and the welding quality at the root of the B area is difficult to control and crystal cracks (thermal cracks) are prone to occur, resulting in poor welding quality and defects. Figure 6As shown in the figure, in order to ensure the quality of the weld, the outer air gouging root cleaning needs to remove part of the deposited metal at the root as much as possible and increase the carbon arc air gouging root cleaning depth (such as Figure 6 The carbon rod consumption increases, the carbon planer workload increases, excessive welding material consumption and extended welding time.

[0053] like Figure 7 and 8 As shown in the figure, the shaded part indicates the root cleaning area. After the groove is improved by the method in Example 1, the root cleaning area is 173.3 mm 2 , in the prior art ( Figure 7 ) has a root cleaning area of ​​715.3mm 2 It can be seen that after improving the groove, the root cleaning depth and root cleaning area at the outer groove are reduced, the labor intensity of the operator is reduced, and the carbonization of the parent material groove is reduced.

[0054] like Figure 9-12 As shown, in the prior art, the front weld area is 3314.4 mm 2 , the back weld area is 888.59mm 2 , the total weld area is 4203.0mm 2 In the present invention, the front weld area is 2498.7mm 2 , the back weld area is 286.1mm 2 The total weld area is 2784.8mm 2 The weld area of ​​the present invention is greatly reduced, welding materials are saved, and production efficiency is improved.

[0055] The above embodiments are only preferred technical solutions of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and modifications without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A welding method for thick steel plate cylinder of offshore wind power, characterized in that: The following steps are involved: S1. Beveling: flame cutting is used to bevel the inner and outer sides of the welds at both ends of the steel plate. A flame is used to pre-open a small-angle X-shaped bevel. The inner bevel is a one-way bevel with an angle of β, β is 14°-16°, and the outer bevel is a one-way bevel with an angle of γ, γ is 30°-40°. The thickness of the cylinder plate is T, the depth T1 of the outer bevel is 14-16mm, the thickness of the blunt edge X between the inner and outer bevels is 2mm, and the depth T2 of the inner bevel is T-T1-X. Then a self-propelled U-shaped beveling machine is used to mechanically mill the cut inner bevel root into a U-shaped bevel. The opening angle of the U-shaped bevel is 13°-18°, and the root of the U-shaped bevel is a fillet with a radius R of 6-10mm. S2. Rolling the cylinder: Roll the steel plate with grooved edges according to the diameter of the cylinder. The cylinder formed after rolling has no gaps at the joints, and the inner groove forms a V+U-shaped semi-narrow gap groove, and the outer groove forms a V-shaped groove; S3, preheating: preheat the groove and surrounding parent materials; S4, positioning welding: positioning welding is performed by using metal-metal gas shielded welding at the blunt edge of the inner side of the formed cylinder; S5. Base welding: Base welding is performed by using metal-metal arc welding at the outer groove of the longitudinal or annular gap of the cylinder that has completed positioning welding; S6. Inner groove welding: For the longitudinal inner weld of the cylinder that has completed the base welding, single-wire submerged arc or double-wire submerged arc automatic welding is used for full welding. The inner seam of the circumferential weld can be welded synchronously by multiple single-wire submerged arc automatic welding machines. S7, Carbon arc gouging and root cleaning: Carbon arc gouging and root cleaning is performed on the outer weld of the cylinder that has completed the inner groove welding; S8. External groove welding: Double-wire submerged arc or single-wire submerged arc automatic welding is used to fully weld the external groove of the cylinder after root cleaning.

2. A method for welding a thick steel plate cylinder for offshore wind power generation as claimed in claim 1, characterized in that: The angle β of the inner groove is 15°, the angle γ of the outer groove is 35°, the thickness T of the cylinder plate is 100 mm, the depth T1 of the outer groove is 15 mm, the thickness of the blunt edge X between the inner groove and the outer groove is 2 mm, the depth T2 of the inner groove is T-T1-X=83 mm, the opening angle of the U-shaped groove is 16°, and the radius R of the fillet is 8 mm.

3. A method for welding a thick steel plate cylinder for offshore wind power generation as claimed in claim 2, characterized in that: After the cylinder is rolled, a 30°V+16°U-shaped semi-narrow gap groove is formed at the inner groove, and a 70°V-shaped groove is formed at the outer groove.

4. A method for welding a thick steel plate cylinder for offshore wind power generation as claimed in claim 1, characterized in that: The preheating temperature is 20℃-120℃. When measuring the preheating temperature, steel plates ≥50mm should be measured at a distance of 75mm from the weld.

5. The method for welding a thick steel plate cylinder for offshore wind power generation as claimed in claim 1, characterized in that: The welding fill thickness during base welding is 7mm-8mm.

6. A method for welding a thick steel plate cylinder for offshore wind power generation as claimed in claim 1, characterized in that: When the carbon arc air planer is used for root cleaning, the outer groove is carbon planed to form a No. 2 U-shaped groove, the angle of the No. 2 U-shaped groove is greater than 16°, and the radius of the fillet should be ≥5mm.

7. A method for welding a thick steel plate cylinder for offshore wind power generation as claimed in claim 1, characterized in that: During positioning welding and backing welding, the wire diameter of the metal electrode gas shielded welding is 1.2mm, the shielding gas used is 100% CO2, the welding current is 180A-280A, the welding voltage is 25V-32V, the welding speed is 150mm / min-320mm / min, and the gas flow rate during welding is 18L / min-25L / min.

8. A method for welding a thick steel plate cylinder for offshore wind power generation as claimed in claim 1, characterized in that: When welding inner groove and outer groove, the diameter of single-wire submerged arc welding wire is 4.0mm. The flux should be dried for 1h before use. The drying temperature is 300℃-350℃. The front wire current during welding is 500A-760A, the front wire voltage during welding is 26V-34V, and the welding speed is 390mm / mim-440mm / min.

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