Metal type flux-cored wire and method for preparing slip ring of wind turbine generator

Abstract

The invention discloses a metal type flux-cored wire which comprises a flux core and an outer skin, the flux core is composed of, by mass, 60%-70% of nickel powder, 22%-25% of titanium powder, 3%-10% of tin powder, 1%-4% of manganese powder, 2%-6% of silicon powder, 1%-2% of vanadium powder and 1%-4% of aluminum powder, and the sum of the mass percentages of the components is 100%; the outer skin is an annealed T2 copper strip, and the filling rate of the powder core wire is 15 wt%; the invention further discloses a method for preparing the wind turbine generator slip ring through the metal type flux-cored wire, surfacing is conducted on the surface of the martensitic stainless steel base material through 3D printing by adopting an additive manufacturing method, and therefore the wind turbine generator slip ring is obtained. According to the wind turbine generator slip ring prepared through the metal type flux-cored wire, the welding residual stress is reduced, the anti-fatigue capacity of a structural part is improved, and the excellent mechanical property is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of metal welding wire and wire arc additive manufacturing, and in particular relates to a metal type flux-cored welding wire, and also relates to a method for preparing a wind turbine slip ring by using the metal type flux-cored welding wire. Background Art

[0002] As the industry's performance requirements for dissimilar metal bonding components continue to increase. Copper and steel have excellent electrical conductivity and high strength respectively. The combination of the two can simultaneously meet the multiple requirements of electrical performance, thermal management and structural load-bearing. In the fields of wind power, aerospace, automobiles, and electronics, many key components need to have both the high thermal conductivity and high electrical conductivity of copper and the mechanical strength and wear resistance of steel. However, traditional processes have many challenges in combining copper and steel, such as interface stress caused by large differences in thermal expansion coefficients, and the high difficulty of welding or casting processes caused by different melting points of the two.

[0003] Metal flux-cored welding wire can be used to weld various types of steel. By adjusting the composition and proportion of the welding wire, the required chemical composition of the weld can be provided. It has strong adaptability. The flux-cored welding wire adopts gas-slag joint protection to obtain good weld formation. Ni has a good promoting effect on metal fluidity and weld formation during welding, can reduce the crack sensitivity generated during welding, and improve the toughness and strength of the welded joint. Flux-cored welding wire with high Ni content can form a more uniform alloying layer during welding, reducing the probability of cracks.

[0004] Wire arc additive manufacturing (WAAM) is an advanced manufacturing technology that uses an electric arc as a heat source to melt metal wire and deposit it layer by layer on a substrate according to a predetermined path. Compared with traditional manufacturing methods, the use of WAAM to manufacture wind turbine slip rings has significant advantages. Traditional methods usually have low precision, complex processing procedures and poor fatigue performance. The use of wire arc additive manufacturing can not only shorten the production cycle and reduce production costs, but also improve material utilization and achieve a high degree of automation. Especially when manufacturing large-sized thin-walled components with complex shapes, WAAM technology shows more outstanding advantages and can effectively improve production efficiency and component quality. Summary of the invention

[0005] The first object of the present invention is to provide a metal-type flux-cored welding wire, which can be used to prepare wind turbine slip rings. The flux-cored welding wire effectively transitions alloy elements into the weld during the welding process through its copper-coated core, thereby improving the composition and structure of the weld joint and significantly reducing the probability of cracks during the welding process.

[0006] The second object of the present invention is to provide a method for preparing a wind turbine slip ring using a metal flux-cored welding wire, which uses wire arc additive manufacturing technology to achieve efficient preparation of wind turbine slip rings during the production process. This method not only greatly shortens the production cycle, but also improves the utilization rate of materials, thereby reducing production costs and ensuring the high quality and performance stability of the slip ring.

[0007] The first technical solution adopted by the present invention is: a metal-type flux-cored welding wire is composed of the following components in mass percentage: nickel powder: 60% to 70%, titanium powder: 22% to 25%, tin powder: 3% to 10%, manganese powder: 1% to 4%, silicon powder: 2% to 6%, vanadium powder: 1% to 2%, aluminum powder: 1% to 4%, and the sum of the mass percentages of the above components is 100%; the outer skin used is an annealed T2 copper strip with a width of 7 mm and a thickness of 0.3 mm, and the filling rate of the powder core wire is 15wt%.

[0008] The second technical solution adopted by the present invention is: a method for preparing a wind turbine slip ring using a metal-type flux-cored welding wire,

[0009] Step 1: Weigh nickel powder: 60%-70%, titanium powder: 22%-25%, tin powder: 3%-10%, manganese powder: 1%-4%, silicon powder: 2%-6%, vanadium powder: 1%-2%, aluminum powder: 1%-4% according to mass percentage, and the sum of the mass percentages of the above components is 100%.

[0010] Step 2, heating the alloy powder weighed in step 1 in an inert gas atmosphere and keeping it warm for a period of time;

[0011] Step 3, the components obtained in step 2 are kept warm and then cooled to room temperature with the furnace, the flux core powder is filled into the U-shaped groove of the copper belt, and after passing through the closed forming roller, it is made into a Φ2.50mm welding wire, and finally a Φ1.2mm metal-type flux cored welding wire is made by a step-by-step diameter reduction method; the outer skin is an annealed T2 copper belt, and the filling rate of the powder core wire is 15wt%.

[0012] Step 4. Select a 12CrNiMoV martensitic stainless steel substrate of appropriate size, use an angle grinder to grind the rust, oil, oxide scale and dust impurities on the surface of the substrate, load the prepared metal-type flux-cored welding wire into the fully automatic welding robot, and select a single-layer multi-pass, reciprocating path to complete a layer of multi-pass accumulation, among which non-linear parts use continuous short-pass straight welding; during the 3D printing process, each layer of accumulation is completed, and the deposition direction needs to be changed when the next layer of additive material is started; the non-linear welding speed is 0.3m / min~0.55m / min, and the linear welding speed range is 0.2m / min~0.35m / min. The welding speed of non-linear parts is faster than that of linear parts by 0. .1m / min~0.2m / min; the parts with thickness less than or equal to 5mm in the parts need to have ±3mm processing allowance; the parts with width ≥10mm in the straight parts adopt the swing arc welding process; the welding speed of the swing arc welding parts is 0.20m / min~0.26m / min, and the swing arc amplitude is 10mm~12mm; the swing arc frequency is 1Hz~2Hz; the swing arc stay time is 0.1~0.2s, and the design spacing ensures that the overlap rate between the channels is 55%~60% when single-layer multi-channel accumulation is performed. The above process is converted into a program and imported into the welding robot, the welding machine command is run, and MIG welding is used as a heat source to perform additive manufacturing on the substrate to obtain the wind turbine slip ring of the present invention.

[0013] Step 5. After the additive manufacturing of the present invention is completed, the welding area is hammered with a hammer to reduce the welding residual stress and improve the fatigue resistance of the structural parts. The usual operation method is: use a 2-5 kg ​​hammer to evenly knock on the welding joint area. The knocking should follow the order of gradual transition from both sides of the weld to the center to ensure uniform distribution of stress. The intensity of the hammering should be adjusted according to the material properties of the weld joint and the degree of residual stress. It is recommended to use a medium force (10-30N impact force) to avoid excessive force causing deformation or cracks in the substrate. The hammering process should maintain a certain frequency and regularity to ensure that external force is evenly applied throughout the welding area.

[0014] The second technical solution of the present invention is also characterized in that:

[0015] The inert atmosphere in step 2 is argon.

[0016] In step 2, the heating temperature is 200-300° C. and the insulation time is 2-3 hours.

[0017] The shielding gas during MIG welding is 80% Ar + 20% CO 2 .

[0018] The beneficial effects of the present invention are:

[0019] (1) The high Ni content of the metal-type flux-cored welding wire of the present invention can enhance the corrosion resistance and oxidation resistance of the welding zone, and help improve the durability of the entire joint. The 12CrNiMoV martensitic stainless steel substrate itself has a certain degree of brittleness, and may easily crack, especially during the cooling process. The flux-cored welding wire with a high Ni content can form a relatively uniform alloy layer during the welding process, reducing the probability of cracks.

[0020] (2) The metal-type flux-cored welding wire of the present invention has a short preparation cycle, high production efficiency, and can achieve continuous production. It can be used for additive manufacturing of complex parts in the fields of wind power, aerospace, automobiles, and electronics.

[0021] (3) The present invention provides a method for preparing a wind turbine pulley based on additive manufacturing technology, using MIG welding as a heat source and metal-type flux-cored welding wire as a raw material; the present invention places a uniformly mixed flux-cored powder in a tubular furnace, continuously introduces argon gas, and keeps the temperature at 200°C to 300°C for 2h to 3h. This method can effectively avoid the oxidation of alloy elements and reduce the content of oxygen elements in the wind turbine pulley; the present invention uses a fully automatic welding robot to additively manufacture the wind turbine pulley, and the additive manufacturing efficiency is high. The wire arc additive manufacturing can be realized by programming the welding robot; the present invention has less spatter and stable arc during the additive manufacturing process, and the weld is beautiful, basically free of collapse, and the weld surface is smooth, without pores and slag inclusions; after the additive manufacturing is completed, the welding area is hammered with a hammer to reduce the welding residual stress and improve the fatigue resistance of the structural parts. The usual operation method is: use a 2-5 kg ​​hammer to evenly knock the welding joint area. The knocking should follow the order of gradual transition from both sides of the weld to the center to ensure uniform distribution of stress. The force of the hammering should be adjusted according to the material properties of the welded joint and the degree of residual stress. It is recommended to use a medium force (10-30N impact force) to avoid excessive force causing deformation or cracks in the substrate. The hammering process should maintain a certain frequency and regularity to ensure that the external force is evenly applied to the entire welding area. The wind turbine pulley manufactured by the present invention based on MIG welding and using metal-type flux-cored welding wire has excellent mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a microstructure diagram of the interface of the stainless steel / copper composite component prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0023] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] The metal-type flux-cored welding wire of the present invention comprises a flux core and an outer sheath, wherein the flux core is composed of the following components in terms of mass percentage: nickel powder: 60% to 70%, titanium powder: 22% to 25%, tin powder: 3% to 10%, manganese powder: 1% to 4%, silicon powder: 2% to 6%, vanadium powder: 1% to 2%, aluminum powder: 1% to 4%, and the sum of the mass percentages of the above components is 100%; the outer sheath is an annealed T2 copper strip, and the filling rate of the flux core wire is 15wt%.

[0025] The role and function of each component in the welding wire are as follows:

[0026] Ni is the main component in the flux core because its melting point is between Cu and Fe. It can form an infinite solid solution with Cu and Fe without producing intermetallic compounds. At the same time, Ni can also improve the toughness of copper-steel welding joints.

[0027] The addition of Sn element can improve the fluidity of Cu element in the molten pool, thereby improving the solubility between copper and steel.

[0028] The Mn element can purify the weld, remove harmful impurities such as oxygen, phosphorus, and sulfur. In addition, the Mn element can also improve the strength of the welded joint.

[0029] The V element can improve the strength of the weld, refine the grains, and reduce the grain growth tendency in the heat-affected zone on the steel side.

[0030] The Al element can increase the hardness of the weld, and can also increase the yield point and tensile strength of the welded joint.

[0031] Si element is mainly used as a deoxidizer, which can combine with FeO in steel to form silicate welding slag with low density, which can be removed. It can also improve the strength and hardness of the weld.

[0032] The method for preparing a wind turbine slip ring using a metal-type flux-cored welding wire of the present invention comprises the following specific steps:

[0033] Step 1: Weigh nickel powder: 60%-70%, titanium powder: 22%-25%, tin powder: 3%-10%, manganese powder: 1%-4%, silicon powder: 2%-6%, vanadium powder: 1%-2%, aluminum powder: 1%-4% according to mass percentage, and the sum of the mass percentages of the above components is 100%.

[0034] Step 2: Mix the components obtained in step 1 and place them in a tube furnace, continue to introduce argon gas, and keep the temperature at 200° C. to 300° C. for 2 h to 3 h.

[0035] Step 3: After the components obtained in step 2 are kept warm, they are cooled to room temperature in the furnace, and the flux core powder is filled into the U-shaped groove of the copper strip, and after passing through the closed forming roller, a Φ2.50 mm welding wire is made, and a Φ1.2 mm metal-type flux cored welding wire is finally made by a step-by-step reduction method. The outer skin is an annealed T2 copper strip, and the filling rate of the powder core wire is 15wt%.

[0036] Step 4: Select a 12CrNiMoV martensitic stainless steel substrate of appropriate size, use an angle grinder to grind the rust, oil, scale and dust impurities on the surface of the substrate, load the prepared metal-type flux-cored welding wire into the fully automatic welding robot, and select a single-layer multi-pass, reciprocating path to complete a layer of multi-pass deposition, where non-linear parts use continuous short-pass straight welding; during the 3D printing process, each layer of deposition is completed, and the deposition direction needs to be changed when the next layer of material is added; the non-linear welding speed is 0.3m / min-0.55m / min, the linear welding speed range is 0.2m / min-0.35m / min, and the non-linear welding speed range is 1.5m / min-2.0m / min. The welding speed of the straight part is 0.1m / min-0.2m / min faster than that of the straight part; the parts with a thickness of less than or equal to 5mm in the parts need to leave a ±3mm processing allowance; the parts with a width of ≥10mm in the straight part adopt the swing arc welding process, and the welding speed of the swing arc welding part is 0.20m / min~0.26m / min, the swing arc amplitude is 10mm-12mm, the swing arc frequency is 1Hz-2Hz, and the swing arc stay time is 0.1-0.2s. When the single layer and multiple channels are stacked, the design spacing ensures that the overlap rate between channels is 55%-60%, and the protective gas is 80% Ar+20% CO 2 The above process is converted into a program and imported into a welding robot, and the welding machine command is run. The wind turbine slip ring of the present invention is obtained by using MIG welding as a heat source to perform additive manufacturing on the substrate.

[0037] Step 5. After the additive manufacturing is completed, tap the welding area with a hammer to reduce the residual stress generated by the wind turbine slip ring structure after the additive process and improve the fatigue resistance of the structure. The usual operation method is: use a 2-5 kg ​​hammer to evenly tap the welding joint area. The tapping should follow the order of gradual transition from both sides of the weld to the center to ensure uniform distribution of stress. The intensity of the hammering should be adjusted according to the material properties of the welded joint and the degree of residual stress. It is recommended to use a medium force (10-30N impact force) to avoid excessive force causing deformation or cracks in the substrate. The hammering process should maintain a certain frequency and regularity to ensure that external force is evenly applied throughout the welding area.

[0038] Example 1

[0039] Step 1: Weigh nickel powder: 70%, titanium powder: 22%, tin powder: 3%, manganese powder: 1%, silicon powder: 2%, vanadium powder: 1%, aluminum powder: 1% by mass percentage, and the sum of the mass percentages of the above components is 100%.

[0040] Step 2: Mix all the raw materials weighed in step 1 evenly and place them in a tube furnace. Keep the mixture at 200° C. for 2 h while continuously introducing argon.

[0041] Step 3: Place an annealed T2 copper strip with a width of 7 mm and a thickness of 0.3 mm on the unwinding machine of a welding wire forming machine, roll the annealed T2 copper strip into a U-shaped groove through the pressing groove of the forming machine, put the flux core powder obtained in step 2 into the U-shaped groove, and control the filling rate of the flux core powder to be 15wt%. Then, use a forming machine to roll and close the U-shaped groove, wipe it clean with acetone or anhydrous ethanol, and then draw it to a diameter of 1.2 mm. Use a cotton cloth dipped in acetone or anhydrous ethanol to wipe the oil stains on the welding wire. Finally, the welding wire is straightened by a wire drawing machine, coiled into a disc, and sealed and packaged to obtain a metal-type flux-cored welding wire for wind turbine slip rings for additive manufacturing.

[0042] Step 4: Select a 12CrNiMoV martensitic stainless steel substrate of appropriate size, use an angle grinder to grind the rust, oil, scale and dust impurities on the surface of the substrate, load the prepared metal cored wire into the fully automatic welding robot, and select a single-layer multi-pass, reciprocating path to complete a layer of multi-pass deposition, where non-linear parts use continuous short-pass straight welding; during the 3D printing process, each layer of deposition is completed, and the deposition direction needs to be changed when starting to add the next layer; the non-linear welding speed is 0.3m / min, and the linear welding speed is 0.2m / min. min, the welding speed of non-linear parts is 0.1m / min faster than that of linear parts; parts with a thickness of less than or equal to 5mm in the parts need to have a processing allowance of ±3mm; parts with a width of ≥10mm in linear parts adopt the swing arc welding process, the welding speed of the swing arc welding parts is 0.20m / min, the swing arc amplitude is 10mm, the swing arc frequency is 1Hz, and the swing arc stay time is 0.1s. When single-layer multi-pass stacking is used, the design spacing ensures that the overlap rate between passes is 55%-60%, and the protective gas is 80% Ar+20% CO 2 The above process is converted into a program and imported into a welding robot, and the welding machine command is run. The wind turbine slip ring of the present invention is obtained by using MIG welding as a heat source to perform additive manufacturing on the substrate.

[0043] Step 5: After the additive manufacturing is completed, use a 2 kg hammer to evenly tap the weld joint area. The tapping should follow the order of gradual transition from both sides of the weld to the center to ensure uniform distribution of stress. The force of the hammering should be adjusted according to the material properties of the weld joint and the degree of residual stress. Use a medium force (15N impact force) to avoid excessive force causing deformation or cracks in the substrate. The hammering process should maintain a certain frequency and regularity to ensure that the external force is evenly applied to the entire welding area. Reduce the residual stress generated by the wind turbine slip ring structure after the additive process and improve the fatigue resistance of the structure.

[0044] Through testing, it can be measured that the tensile strength of the wind turbine slip ring is 372.1Mpa.

[0045] from Figure 1 It can be seen that the microstructure interface of the wind turbine slip ring prepared by this method achieves a gradient transition, no obvious defects are found, and the interface bonding is good.

[0046] Example 2

[0047] Step 1: Weigh nickel powder: 67%, titanium powder: 25%, tin powder: 3%, manganese powder: 1%, silicon powder: 2%, vanadium powder: 1%, aluminum powder: 1% by mass percentage, and the sum of the mass percentages of the above components is 100%.

[0048] Step 2: Mix all the raw materials weighed in step 1 evenly, place in a tube furnace, and keep warm at 230° C. for 3 h while continuously passing argon gas.

[0049] Step 3: Place an annealed T2 copper strip with a width of 7 mm and a thickness of 0.3 mm on the unwinding machine of a welding wire forming machine, roll the annealed T2 copper strip into a U-shaped groove through the pressing groove of the forming machine, put the flux core powder obtained in step 2 into the U-shaped groove, and control the filling rate of the flux core powder to be 15wt%. Then, use a forming machine to roll and close the U-shaped groove, wipe it clean with acetone or anhydrous ethanol, and then draw it to a diameter of 1.2 mm. Use a cotton cloth dipped in acetone or anhydrous ethanol to wipe the oil stains on the welding wire. Finally, the welding wire is straightened by a wire drawing machine, coiled into a disc, and sealed and packaged to obtain a metal-type flux-cored welding wire for wind turbine slip rings for additive manufacturing.

[0050] Step 4: Select a 12CrNiMoV martensitic stainless steel substrate of appropriate size, use an angle grinder to grind the rust, oil, scale and dust impurities on the surface of the substrate, load the prepared metal cored wire into the fully automatic welding robot, and select a single-layer multi-pass, reciprocating path to complete a layer of multi-pass deposition, where non-linear parts use continuous short-pass straight welding; during the 3D printing process, each layer of deposition is completed, and the deposition direction needs to be changed when starting to add the next layer; the non-linear welding speed is 0.3m / min, and the linear welding speed range is 0.2m / min / min, the welding speed of non-linear parts is 0.1m / min faster than that of linear parts; parts with a thickness of less than or equal to 5mm in the parts need to have a processing allowance of ±3mm; parts with a width of ≥10mm in linear parts adopt the swing arc welding process, the welding speed of the swing arc welding parts is 0.20m / min, the swing arc amplitude is 10mm, the swing arc frequency is 1Hz, and the swing arc stay time is 0.1s. When single-layer multi-pass stacking is used, the design spacing ensures that the overlap rate between passes is 55%-60%, and the protective gas is 80% Ar+20% CO 2 The above process is converted into a program and imported into a welding robot, and the welding machine command is run. The wind turbine slip ring of the present invention is obtained by using MIG welding as a heat source to perform additive manufacturing on the substrate.

[0051] Step 5: After the additive manufacturing is completed, use a 2 kg hammer to evenly tap the weld joint area. The tapping should follow the order of gradual transition from both sides of the weld to the center to ensure uniform distribution of stress. The force of the hammering should be adjusted according to the material properties of the weld joint and the degree of residual stress. Use a medium force (15N impact force) to avoid excessive force causing deformation or cracks in the substrate. The hammering process should maintain a certain frequency and regularity to ensure that the external force is evenly applied to the entire welding area. Reduce the residual stress generated by the wind turbine slip ring structure after the additive process and improve the fatigue resistance of the structure.

[0052] Through testing, it can be measured that the tensile strength of the wind turbine slip ring is 365.5Mpa.

[0053] Example 3

[0054] Step 1: Weigh nickel powder: 64%, titanium powder: 22%, tin powder: 5%, manganese powder: 2%, silicon powder: 2%, vanadium powder: 1%, aluminum powder: 4% by mass percentage, and the sum of the mass percentages of the above components is 100%.

[0055] Step 2: Mix all the raw materials weighed in step 1 evenly, place in a tube furnace, and keep warm at 250° C. for 2.5 h while continuously passing argon gas.

[0056] Step 3: Place an annealed T2 copper strip with a width of 7 mm and a thickness of 0.3 mm on the unwinding machine of a welding wire forming machine, roll the annealed T2 copper strip into a U-shaped groove through the pressing groove of the forming machine, put the flux core powder obtained in step 2 into the U-shaped groove, and control the filling rate of the flux core powder to be 15wt%. Then, use a forming machine to roll and close the U-shaped groove, wipe it clean with acetone or anhydrous ethanol, and then draw it to a diameter of 1.2 mm. Use a cotton cloth dipped in acetone or anhydrous ethanol to wipe the oil stains on the welding wire. Finally, the welding wire is straightened by a wire drawing machine, coiled into a disc, and sealed and packaged to obtain a wind turbine slip ring flux cored welding wire for additive manufacturing.

[0057] Step 4: Select a 12CrNiMoV martensitic stainless steel substrate of appropriate size, use an angle grinder to grind the rust, oil, scale and dust impurities on the surface of the substrate, load the prepared metal flux-cored wire into the fully automatic welding robot, and select a single-layer multi-pass, reciprocating path to complete a layer of multi-pass deposition, where non-linear parts use continuous short-pass straight welding; during the 3D printing process, each layer of material is deposited, and the deposition direction needs to be changed when the next layer of material is added; the non-linear welding speed is 0.3m / min, and the linear welding speed range is 0.2 m / min, the welding speed of non-linear parts is 0.1m / min faster than that of linear parts; parts with a thickness of less than or equal to 5mm in the parts need to have a processing allowance of ±3mm; parts with a width of ≥10mm in linear parts adopt the swing arc welding process, the welding speed of the swing arc welding parts is 0.20m / min, the swing arc amplitude is 10mm, the swing arc frequency is 1Hz, and the swing arc stay time is 0.1. When single-layer multi-pass stacking is used, the design spacing ensures that the overlap rate between passes is 55%-60%, and the protective gas is 80% Ar+20% CO 2 The above process is converted into a program and imported into a welding robot, and the welding machine command is run. The wind turbine slip ring of the present invention is obtained by using MIG welding as a heat source to perform additive manufacturing on the substrate.

[0058] Step 5: After the additive manufacturing is completed, use a 2 kg hammer to evenly tap the weld joint area. The tapping should follow the order of gradual transition from both sides of the weld to the center to ensure uniform distribution of stress. The force of the hammering should be adjusted according to the material properties of the weld joint and the degree of residual stress. Use a medium force (15N impact force) to avoid excessive force causing deformation or cracks in the substrate. The hammering process should maintain a certain frequency and regularity to ensure that the external force is evenly applied to the entire welding area. Reduce the residual stress generated by the wind turbine slip ring structure after the additive process and improve the fatigue resistance of the structure.

[0059] Through testing, it can be measured that the tensile strength of the wind turbine slip ring is 369.7Mpa.

[0060] Example 4

[0061] Step 1: Weigh nickel powder: 65%, titanium powder: 25%, tin powder: 3%, manganese powder: 3%, silicon powder: 2%, vanadium powder: 1%, aluminum powder: 1% by mass percentage, and the sum of the mass percentages of the above components is 100%.

[0062] Step 2: Mix all the raw materials weighed in step 1 evenly, place in a tube furnace, continuously introduce argon, and keep warm at 280°C for 2h.

[0063] Step 3: Place an annealed T2 copper strip with a width of 7 mm and a thickness of 0.3 mm on the unwinding machine of a welding wire forming machine, roll the annealed T2 copper strip into a U-shaped groove through the pressing groove of the forming machine, put the flux core powder obtained in step 2 into the U-shaped groove, and control the filling rate of the flux core powder to be 15wt%. Then, use a forming machine to roll and close the U-shaped groove, wipe it clean with acetone or anhydrous ethanol, and then draw it to a diameter of 1.2 mm. Use a cotton cloth dipped in acetone or anhydrous ethanol to wipe the oil stains on the welding wire. Finally, the welding wire is straightened by a wire drawing machine, coiled into a disc, and sealed and packaged to obtain a metal-type flux-cored welding wire for wind turbine slip rings for additive manufacturing.

[0064] Step 4: Select a 12CrNiMoV martensitic stainless steel substrate of appropriate size, use an angle grinder to grind the rust, oil, scale and dust impurities on the surface of the substrate, load the prepared metal flux-cored wire into the fully automatic welding robot, and select a single-layer multi-pass, reciprocating path to complete a layer of multi-pass deposition, where non-linear parts use continuous short-pass straight welding; during the 3D printing process, each layer of material is deposited, and the deposition direction needs to be changed when the next layer of material is added; the non-linear welding speed is 0.3m / min, and the linear welding speed range is 0.2 m / min, the welding speed of non-linear parts is 0.1m / min faster than that of linear parts; parts with a thickness of less than or equal to 5mm in the parts need to have a processing allowance of ±3mm; parts with a width of ≥10mm in linear parts adopt the swing arc welding process, the welding speed of the swing arc welding parts is 0.20m / min, the swing arc amplitude is 10mm, the swing arc frequency is 1Hz, and the swing arc stay time is 0.1. When single-layer multi-pass stacking is used, the design spacing ensures that the overlap rate between passes is 55%-60%, and the protective gas is 80% Ar+20% CO 2 The above process is converted into a program and imported into a welding robot, and the welding machine command is run. The wind turbine slip ring of the present invention is obtained by using MIG welding as a heat source to perform additive manufacturing on the substrate.

[0065] Step 5: After the additive manufacturing is completed, use a 2 kg hammer to evenly tap the weld joint area. The tapping should follow the order of gradual transition from both sides of the weld to the center to ensure uniform distribution of stress. The force of the hammering should be adjusted according to the material properties of the weld joint and the degree of residual stress. Use a medium force (15N impact force) to avoid excessive force causing deformation or cracks in the substrate. The hammering process should maintain a certain frequency and regularity to ensure that the external force is evenly applied to the entire welding area. Reduce the residual stress generated by the wind turbine slip ring structure after the additive process and improve the fatigue resistance of the structure.

[0066] Through testing, it can be measured that the tensile strength of the wind turbine slip ring is 367.8Mpa.

[0067] Example 5

[0068] Step 1: Weigh nickel powder: 62%, titanium powder: 23%, tin powder: 3%, manganese powder: 4%, silicon powder: 3%, vanadium powder: 2%, aluminum powder: 3% by mass percentage, and the sum of the mass percentages of the above components is 100%.

[0069] Step 2: Mix all the raw materials weighed in step 1 evenly, place in a tube furnace, continuously introduce argon, and keep warm at 300°C for 2h.

[0070] Step 3: Place an annealed T2 copper strip with a width of 7 mm and a thickness of 0.3 mm on the unwinding machine of a welding wire forming machine, roll the annealed T2 copper strip into a U-shaped groove through the pressing groove of the forming machine, put the flux core powder obtained in step 2 into the U-shaped groove, and control the filling rate of the flux core powder to 15wt%. Then, use a forming machine to roll and close the U-shaped groove, wipe it clean with acetone or anhydrous ethanol, and then draw it to a diameter of 1.2 mm. Use a cotton cloth dipped in acetone or anhydrous ethanol to wipe the oil stains on the welding wire. Finally, the welding wire is straightened by a wire drawing machine, coiled into a disc, and sealed and packaged to obtain a metal-type flux-cored welding wire for wind turbine slip rings for additive manufacturing.

[0071] Step 4: Select a 12CrNiMoV martensitic stainless steel substrate of appropriate size, use an angle grinder to grind the rust, oil, scale and dust impurities on the surface of the substrate, load the prepared metal flux-cored wire into the fully automatic welding robot, and select a single-layer multi-pass, reciprocating path to complete a layer of multi-pass deposition, where non-linear parts use continuous short-pass straight welding; during the 3D printing process, each layer of material is deposited, and the deposition direction needs to be changed when the next layer of material is added; the non-linear welding speed is 0.3m / min, and the linear welding speed range is 0.2 m / min, the welding speed of non-linear parts is 0.1m / min faster than that of linear parts; parts with a thickness of less than or equal to 5mm in the parts need to have a processing allowance of ±3mm; parts with a width of ≥10mm in linear parts adopt the swing arc welding process, the welding speed of the swing arc welding parts is 0.20m / min, the swing arc amplitude is 10mm, the swing arc frequency is 1Hz, and the swing arc stay time is 0.1. When single-layer multi-pass stacking is used, the design spacing ensures that the overlap rate between passes is 55%-60%, and the protective gas is 80% Ar+20% CO 2 The above process is converted into a program and imported into a welding robot, and the welding machine command is run. The wind turbine slip ring of the present invention is obtained by using MIG welding as a heat source to perform additive manufacturing on the substrate.

[0072] Step 5: After the additive manufacturing is completed, use a 2 kg hammer to evenly tap the weld joint area. The tapping should follow the order of gradual transition from both sides of the weld to the center to ensure uniform distribution of stress. The force of the hammering should be adjusted according to the material properties of the weld joint and the degree of residual stress. Use a medium force (15N impact force) to avoid excessive force causing deformation or cracks in the substrate. The hammering process should maintain a certain frequency and regularity to ensure that the external force is evenly applied to the entire welding area. Reduce the residual stress generated by the wind turbine slip ring structure after the additive process and improve the fatigue resistance of the structure.

[0073] Through testing, it can be measured that the tensile strength of the wind turbine slip ring is 379.2Mpa.

[0074] Example 6

[0075] Step 1: Weigh nickel powder: 62%, titanium powder: 23%, tin powder: 3%, manganese powder: 4%, silicon powder: 5%, vanadium powder: 2%, aluminum powder: 1% by mass percentage, and the sum of the mass percentages of the above components is 100%.

[0076] Step 2: Mix all the raw materials weighed in step 1 evenly, place in a tube furnace, continuously introduce argon, and keep warm at 300°C for 2h.

[0077] Step 3: Place an annealed T2 copper strip with a width of 7 mm and a thickness of 0.3 mm on the unwinding machine of a welding wire forming machine, roll the annealed T2 copper strip into a U-shaped groove through the pressing groove of the forming machine, put the flux core powder obtained in step 2 into the U-shaped groove, and control the filling rate of the flux core powder to 15wt%. Then, use a forming machine to roll and close the U-shaped groove, wipe it clean with acetone or anhydrous ethanol, and then draw it to a diameter of 1.2 mm. Use a cotton cloth dipped in acetone or anhydrous ethanol to wipe the oil stains on the welding wire. Finally, the welding wire is straightened by a wire drawing machine, coiled into a disc, and sealed and packaged to obtain a metal-type flux-cored welding wire for wind turbine slip rings for additive manufacturing.

[0078] Step 4: Select a 12CrNiMoV martensitic stainless steel substrate of appropriate size, use an angle grinder to grind the rust, oil, scale and dust impurities on the surface of the substrate, load the prepared metal flux-cored wire into the fully automatic welding robot, and select a single-layer multi-pass, reciprocating path to complete a layer of multi-pass deposition, where non-linear parts use continuous short-pass straight welding; during the 3D printing process, each layer of material is deposited, and the deposition direction needs to be changed when the next layer of material is added; the non-linear welding speed is 0.3m / min, and the linear welding speed range is 0.2 m / min, the welding speed of non-linear parts is 0.1m / min faster than that of linear parts; parts with a thickness of less than or equal to 5mm in the parts need to have a processing allowance of ±3mm; parts with a width of ≥10mm in linear parts adopt the swing arc welding process, the welding speed of the swing arc welding parts is 0.20m / min, the swing arc amplitude is 10mm, the swing arc frequency is 1Hz, and the swing arc stay time is 0.1. When single-layer multi-pass stacking is used, the design spacing ensures that the overlap rate between passes is 55%-60%, and the protective gas is 80% Ar+20% CO 2 The above process is converted into a program and imported into a welding robot, and the welding machine command is run. The wind turbine slip ring of the present invention is obtained by using MIG welding as a heat source to perform additive manufacturing on the substrate.

[0079] Step 5: After the additive manufacturing is completed, use a 2 kg hammer to evenly tap the weld joint area. The tapping should follow the order of gradual transition from both sides of the weld to the center to ensure uniform distribution of stress. The force of the hammering should be adjusted according to the material properties of the weld joint and the degree of residual stress. Use a medium force (15N impact force) to avoid excessive force causing deformation or cracks in the substrate. The hammering process should maintain a certain frequency and regularity to ensure that the external force is evenly applied to the entire welding area. Reduce the residual stress generated by the wind turbine slip ring structure after the additive process and improve the fatigue resistance of the structure.

[0080] Through testing, it can be measured that the tensile strength of the wind turbine slip ring is 375.7Mpa.

[0081] The technical solution of the present invention is compared with the solid welding wire. The flux-cored welding wire uses the flux core in the copper strip to transfer the alloy elements to the weld during the welding process, so it is very convenient to adjust the content of the alloy components. The solid welding wire needs to be re-smelted every time the alloy components are adjusted.

[0082] The present invention adopts MIG welding to provide a heat source for preparing the slip ring of the wind turbine set, and CO 2 Compared with gas shielded welding, MIG welding has a stable arc, stable droplet transition, less welding spatter, and good weld formability; compared with TIG welding, MIG welding uses welding wire as an electrode, with high welding wire and current density, high welding wire melting efficiency, small welding deformation, high productivity, and is suitable for automated production. During TIG welding, a small amount of tungsten melts and evaporates. Tungsten particles entering the molten pool will cause tungsten inclusions, affecting welding quality. In addition, TIG welding has limited carrying current, the arc is easy to expand, difficult to concentrate, and the weld has a small penetration depth.

[0083] Based on MIG welding, the present invention uses metal-type flux-cored welding wire as raw material to prepare wind turbine slip rings, which has the following advantages: high weld metal deposition rate, high production efficiency, good structural part formability, no slag inclusion in the weld, low cost, and suitable for automated production; small spatter during welding and stable droplet transition.

[0084] The tensile strength of the wind turbine slip ring structure prepared by the patent example of the present invention is 365.5Mpa~379.2Mpa, which is greater than the wind turbine slip ring structure prepared by the current MIG welding arc additive manufacturing technology.

Claims

1. Metal type flux-cored welding wire, characterized in that: The welding wire comprises a flux core and a sheath, wherein the flux core is composed of the following components in mass percentage: nickel powder: 60% to 70%, titanium powder: 22% to 25%, tin powder: 3% to 10%, manganese powder: 1% to 4%, silicon powder: 2% to 6%, vanadium powder: 1% to 2%, aluminum powder: 1% to 4%, and the sum of the mass percentages of the above components is 100%; the sheath is annealed T2 copper strip, and the filling rate is 15wt%.

2. A method for preparing a wind turbine slip ring using a metal-type flux-cored welding wire, characterized in that: By using metal-type flux-cored welding wire and the additive manufacturing method, 3D printing is used to perform surfacing on the surface of the martensitic stainless steel substrate to obtain the wind turbine slip ring.

3. The method for preparing a wind turbine slip ring using a metal-type flux-cored welding wire according to claim 2, characterized in that: The specific steps are as follows: Step 1, weighing nickel powder: 60% to 70%, titanium powder: 22% to 25%, tin powder: 3% to 10%, manganese powder: 1% to 4%, silicon powder: 2% to 6%, vanadium powder: 1% to 2%, aluminum powder: 1% to 4% respectively according to mass percentage, and the sum of the mass percentages of the above components is 100%; Step 2, heating the core powder weighed in step 1 in an inert gas atmosphere and keeping it warm for a period of time; Step 3, the flux core powder obtained in step 2 is kept warm and then cooled to room temperature with the furnace, the flux core powder is filled into the U-shaped groove of the annealed T2 copper strip, and is made into welding wire after passing through a closed forming roller, and finally made into a Φ1.2mm metal-type flux cored welding wire by a step-by-step diameter reduction method; Step 4, select a 12CrNiMoV martensitic stainless steel substrate, use an angle grinder to grind the rust, oil, scale and dust impurities on the surface of the substrate, load the prepared metal cored welding wire into a fully automatic welding robot, and select a single-layer multi-pass, reciprocating path to complete a layer of multi-pass deposition, wherein non-linear parts use continuous short-pass straight welding; during the 3D printing process, each additive completes a layer of deposition, and the deposition direction needs to be changed when starting to add the next layer; MIG welding is used as a heat source to perform additive manufacturing on the substrate to obtain the wind turbine slip ring of the present invention; Step 5: After the additive manufacturing is completed, use a hammer to hammer the welding area to reduce the welding residual stress and improve the fatigue resistance of the structural parts.

4. The method for preparing a wind turbine slip ring using a metal-type flux-cored welding wire according to claim 3, characterized in that: The inert atmosphere in step 2 is argon.

5. The method for preparing a wind turbine slip ring using a metal-type flux-cored welding wire according to claim 3, characterized in that: In step 2, the heating temperature is 200-300° C. and the insulation time is 2-3 hours.

6. The method for preparing a wind turbine slip ring using a metal-type flux-cored welding wire according to claim 3, characterized in that: Step 3: The welding wire Φ2.50mm is made by the closed forming roller.

7. The method for preparing a wind turbine slip ring using a metal-type flux-cored welding wire according to claim 3, characterized in that: In step 4, the non-linear welding speed is 0.3m / min~0.55m / min, and the linear welding speed range is 0.2m / min~0.35m / min; the parts with a thickness of less than or equal to 5mm in the parts need to have a processing allowance of ±3mm; the linear parts with a width of ≥10mm use the swing arc welding process.

8. The method for preparing a wind turbine slip ring using a metal-type flux-cored welding wire according to claim 7, characterized in that: The welding speed of the swing arc welding part is 0.20m / min~0.26m / min, the swing arc amplitude is 10mm~12mm; the swing arc frequency is 1Hz~2Hz; the swing arc dwell time is 0.1~0.2s, and the design spacing ensures that the overlap rate between the passes is 55%~60% when single-layer multi-pass stacking is used.

9. The method for preparing a wind turbine slip ring using a metal-type flux-cored welding wire according to claim 3, characterized in that: Step 5: Use a hammer to strike the welding area. Use a 2-5 kg ​​hammer to strike the welding joint area evenly. The striking should follow the order of gradual transition from both sides of the weld to the center to ensure uniform distribution of stress. The hammering force should be 10-30N. The hammering process should maintain a fixed frequency and regularity to ensure that external force is evenly applied to the entire welding area.

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