Wind power hollow main shaft, and profiling forging process therefor and use thereof

Abstract

A profiling forging process for a wind power hollow main shaft. The profiling forging process comprises the following steps: S1, hot charging of a blank, involving: smelting alloying elements according to a formula, and pouring same into steel ingots, followed by hot charging of the steel ingots; S2, drawing-out and upsetting, involving: after the hot-charged steel ingots in S1 are heated, subjecting same to primary drawing-out, primary upsetting, secondary drawing-out, and secondary upsetting and forging; S3, punching of steel ingots, involving: returning the steel ingots which have been repeatedly drawn out and upset in S2 to a furnace for heating, and then punching same; S4, drawing-out and rounding, involving: returning forged pieces punched in S3 to the furnace for heating, and then subjecting same to shaft body drawing-out and rounding; and S5, controlled cooling after forging, involving: placing the forged pieces obtained in step S4 into an insulated barrel for slow cooling, and then cooling same to room temperature in air, so as to obtain a finished wind power hollow main shaft product. A wind power hollow main shaft obtained on the basis of the forging process, the use of the wind power hollow main shaft in a wind power generator set, and a wind power generator set comprising the wind power hollow main shaft. Under coordinated regulation and control of components, deformation and temperature, a complex-phase structure consisting of a matrix phase and an MnNi phase, that is distributed at a grain boundary, at a normal temperature is obtained by means of the forging process; and the wind power hollow main shaft obtained by means of the process has good low-temperature impact performance.

Description

A wind power hollow main shaft and its copy forging process and application Technical Field

[0001] The invention relates to a wind power hollow main shaft and a profile forging process and application thereof, belonging to the technical field of wind power main shaft manufacturing. Background Art

[0002] Against the backdrop of global energy conservation and emission reduction, reducing reliance on fossil fuels and increasing the use of solar and wind energy have become a global consensus. my country boasts superior wind resources and abundant potential for development. As a new clean energy source, wind power generation has become a national priority and is experiencing rapid growth.

[0003] The wind turbine main shaft is a critical component in a wind turbine, connecting the blade hub and gearbox and transmitting kinetic energy. Currently, the design life of a wind turbine is twenty years. As the primary load-bearing component in a wind turbine, the wind turbine main shaft, exposed to long-term service in harsh environments such as low temperatures, is prone to ductile-brittle transitions, resulting in fractures and accidents. Furthermore, due to the high cost and difficulty of replacing wind turbine main shafts, wind turbine manufacturers place extremely stringent requirements on them. At the same time, the capacity of single wind turbine units has continued to increase in recent years. To improve the utilization rate of wind energy, reduce the area of ​​wind farms, and enhance the economic benefits of wind power, large-capacity wind turbines are becoming the future trend of wind power development. However, the large-scale development of wind turbines will inevitably require the wind turbine main shaft to withstand even harsher environments, requiring it to possess a higher resistance to low-temperature brittle fracture.

[0004] Therefore, it is urgent to study the short-process contour forging process of wind turbine main shaft to solve the low-temperature brittle fracture problem of the above-mentioned wind turbine main shaft forgings.

[0005] Summary of the Invention

[0006] The present invention aims to provide a wind power hollow main shaft copy forging process, which obtains a complex phase structure of a matrix phase and a grain boundary distributed MnNi phase at room temperature under the coordinated regulation of composition, deformation and temperature.

[0007] At the same time, the present invention provides a wind power hollow main shaft that is resistant to low-temperature brittle fracture.

[0008] At the same time, the present invention provides an application of a wind power hollow main shaft in a wind power generator set.

[0009] At the same time, the present invention provides a wind turbine generator set, which includes the wind turbine hollow main shaft of the present invention.

[0010] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0011] A wind power hollow main shaft copy forging process, comprising the following steps:

[0012] S1, hot delivery of billets: alloy elements are melted according to the formula and cast into ingots, and then the ingots are hot delivered;

[0013] S2, drawing and upsetting: after heating the hot-delivered steel ingot of S1, it is subjected to the first drawing, the first upsetting, the second drawing and the second upsetting forging;

[0014] S3, steel ingot punching: repeatedly stretch and upset the steel ingot in S2, return it to the furnace for heating, and then punch it;

[0015] S4, drawing and rounding: after the forgings are punched in S3, they are returned to the furnace for heating and then the shaft body is drawn and rounded;

[0016] S5, controlled cooling after forging: the forging obtained in S4 is placed in an insulation barrel for slow cooling, and then air-cooled to room temperature to obtain the finished wind power hollow main shaft.

[0017] In S1, the metal element components in the formula are calculated by mass percentage: C: 0.36% to 0.42%, Si: 0.15% to 0.25%, Mn: 1.21% to 1.73%, Ni: 1.27% to 2.11%, P: ≤0.02%, S: ≤0.02%, Cr: 0.91% to 1.18%, Mo: 0.22% to 0.29%, Cu: ≤0.1%, V: 0.03% to 0.12%, Sn≤0.002%, Sb≤0.001%, and the balance is Fe.

[0018] In S1, the mass ratio of Mn and Ni in the formula is: Mn:Ni=1:(1.05~1.22).

[0019] In S1, the hot delivery of the steel ingot is to place the steel ingot in an insulation barrel at 850-880° C. after demoulding the steel ingot and to keep it hot.

[0020] In S2, before forging, the hot-sent steel ingot is heated to 1260-1280°C at a heating rate of 70-80°C / h and kept warm for 5-6h.

[0021] In S2, primary drawing, primary upsetting, secondary drawing and secondary upsetting forging are performed, with the primary drawing ratio being 6.1-6.5, the primary upsetting ratio being 6.7-7.2, the secondary drawing ratio being 3.3-3.6, and the secondary upsetting ratio being 3.8-4.1. The primary drawing and primary upsetting are completed within a temperature range of 1080-1260°C, and the secondary drawing and secondary upsetting are completed within a temperature range of 980-1080°C.

[0022] In S3, the punching is performed downward twice with the punch head. The first punching temperature is 1150-1180°C, and the punching is stopped when the ingot is 2 / 3 deep. The forging is then returned to the furnace and heated to 1150-1180°C at 80-90°C / h. The forging is then turned 180° and placed for a second reverse punching until the ingot is punched through.

[0023] In S4, the steel is returned to the furnace and heated to 1200-1220°C at 50-60°C / h before being drawn. The drawing process is as follows: anvil width ratio of 0.6-0.8, reduction of 80-100 mm, 90° clockwise turning, and feed amount of 0.4-0.6 of the anvil width to obtain a drawn forging.

[0024] In S4, the drawn forging is rounded, and the rounding process is as follows: 700-980°C, anvil width ratio of 0.8-0.9, reduction of 10-20 mm, and feed of 0.7-0.8 of the anvil width.

[0025] In S4, before rounding, the drawn forging is returned to the furnace and heated to 1200-1220°C and then rounded.

[0026] In S5, the slow cooling rate in the heat preservation barrel is 5-10°C / h, and after slow cooling to 180-200°C, the product is taken out and air-cooled to room temperature.

[0027] The invention discloses a wind power hollow main shaft obtained by a wind power hollow main shaft copying forging process.

[0028] The grain size of wind power hollow main shaft is 7 to 8 levels.

[0029] The microstructure distribution of the wind turbine hollow main shaft is a composite structure of matrix phase and MnNi phase distributed at grain boundaries.

[0030] The tensile strength of the wind turbine hollow main shaft is 921-981 MPa, the yield strength is 803-936 MPa, the hardness is 336-391 HB, and the -40°C impact AKV / J is 105-109.

[0031] Application of the wind power hollow main shaft of the present invention in a wind power generator set.

[0032] A wind turbine generator set comprises the wind turbine hollow main shaft of the present invention.

[0033] The wind power hollow main shaft finished product of the present invention has excellent low-temperature impact performance.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. The hollow main shaft of wind power generated by the form-forging of the present invention has excellent low-temperature impact performance. The present invention adopts a high ratio of Mn and Ni elements and the coordinated control of high-temperature-medium-high-temperature-medium-temperature step-type temperature changes and large-medium-micro deformation amounts during the form-forging process, so as to achieve a microstructure of the hollow main shaft after form-forging that is a complex phase structure of matrix phase and MnNi phase distributed at the grain boundaries, wherein the matrix phase has fine grains and has good strength and toughness, and the MnNi phase distributed at the grain boundaries is an FCC structure with excellent plasticity and toughness. On the one hand, since the FCC structure does not exhibit low-temperature brittleness, the presence of the MnNi phase at the grain boundaries can significantly improve the overall low-temperature toughness of the forging, thereby enhancing the low-temperature impact performance of the forging; on the other hand, the FCC structure has excellent plasticity and toughness, and can effectively prevent crack propagation during the low-temperature impact process, further improving the low-temperature impact performance of the forging.

[0036] 2. The process of forming the complex phase structure of the wind power hollow main shaft by the contour forging of the present invention is as follows: the first step is to prepare a steel ingot with high Mn and Ni elements in a specific ratio of Mn:Ni=1:(1.05-1.22), which provides the material basis for the subsequent formation of the FCC structure MnNi phase; the second step is a high-temperature (1080-1260°C) high-deformation forging process of primary drawing and primary upsetting, which not only breaks up large grains but also accelerates the diffusion rate of Mn and Ni elements; the third step is a medium-high-temperature (980-1080°C) secondary drawing and secondary upsetting, which not only refines the grains inside the forging and increases the density of defects such as grain boundaries, but also causes Mn and Ni elements to gather at high free energy grain boundaries to form Mn and Ni-rich regions; the fourth step is a low-deformation process during the medium-temperature (700-980°C) drawing and rounding process, which promotes the nucleation and growth of MnNi phases in the Mn and Ni-rich regions at the grain boundaries, ultimately forming the FCC structure microstructure.

[0037] 3. The contour-forged wind turbine hollow main shaft of the present invention can form a room-temperature stable FCC structure MnNi phase during the preparation process. Usually, the FCC structure phase formed at high temperature will undergo phase transformation during heat treatment or cooling due to the high stacking fault energy in the structure, and transform into other forms of crystal structure. For example, the FCC structure austenite of low carbon steel transforms into BCC structure martensite during cooling. However, the present invention improves the stability of the FCC structure in the material system by mixing high Mn and Ni elements in the first step, providing a material basis for the formation of FCC structure MnNi phase at room temperature; subsequently, during the preparation process, through the high-temperature large deformation of a single drawing-single upsetting and the medium-high-temperature medium deformation of a secondary drawing-secondary upsetting, the material is continuously and fully provided with conditions for multiple distortion-dynamic recrystallization processes, thereby reducing stacking faults, reducing stacking fault energy, and forming a stacking fault energy effect. Finally, during the low-temperature, stretching and rounding process, while maintaining a specific temperature and deformation, the low-stacking-fault-energy grains continue to grow while further reducing the stacking fault energy, thereby strengthening the stability of the FCC structure. Ultimately, through the coordinated control of composition, deformation, and temperature, the composite structure of the present invention is achieved at room temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] FIG1 is a microstructure diagram of the wind power hollow main shaft of the present invention;

[0039] FIG2 is a microstructure diagram of a comparative example. DETAILED DESCRIPTION

[0040] The present invention will be further described in detail below with reference to the accompanying drawings and specific examples. The following examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0041] Example 1

[0042] A wind power hollow main shaft copy forging process, comprising the following steps:

[0043] S1, hot delivery billet: alloy elements are melted according to the formula and cast into ingots, and then the ingots are hot delivered; the hot delivery ingots are placed in an insulation barrel at 850°C after demoulding; the metal element composition in the formula is as follows by mass percentage: C: 0.36%, Si: 0.15%, Mn: 1.21%, Ni: 1.27%, P: 0.02%, S: 0.02%, Cr: 0.91%, Mo: 0.22%, Cu: 0.1%, V: 0.03%, Sn: 0.002%, Sb: 0.001%, and the balance is Fe; the mass ratio of Mn to Ni in the formula is: Mn:Ni = 1:1.05;

[0044] S2, drawing and upsetting: After heating the S1 hot-delivered steel ingot, it is subjected to the following steps: first drawing - first upsetting - second drawing - second upsetting forging; before forging, the hot-delivered steel ingot is heated to 1260°C at a heating rate of 70°C / h and kept at this temperature for 5h;

[0045] The first drawing ratio is 6.1, the first upsetting ratio is 6.7, the second drawing ratio is 3.3, and the second upsetting ratio is 3.8. The first drawing-first upsetting is completed at 1080℃, and the second drawing-second upsetting is completed at 980℃.

[0046] S3, ingot punching: The S2 ingot is repeatedly stretched and upset, then remelted and heated for punching. The punch is punched downward twice, with the first punching temperature at 1150°C. The punching is stopped when the ingot reaches 2 / 3 of its depth. The ingot is then remelted and heated at 80°C / h to 1150°C. The forging is then turned 180° and placed for a second reverse punching until the ingot is punched through.

[0047] S4, drawing and rounding: The forgings after punching in S3 are returned to the furnace for heating and then subjected to shaft drawing and rounding; the forgings are heated to 1200°C at 50°C / h and then drawn. The drawing process is as follows: anvil width ratio of 0.6, reduction of 80mm, 90° clockwise turning, and feed of 0.4 of the anvil width to obtain a drawn forging; the drawn forgings are rounded. Before rounding, the drawn forgings are returned to the furnace for heating to 1200°C and then rounded. The rounding process is as follows: anvil width ratio of 0.8, reduction of 10mm, and feed of 0.7 of the anvil width at 700°C;

[0048] S5, controlled cooling after forging: the forging obtained in S4 is placed in an insulation barrel for slow cooling, and then air-cooled to room temperature to obtain a finished wind power hollow main shaft; the slow cooling rate in the insulation barrel is 5°C / h, and after slow cooling to 180°C, it is taken out and air-cooled to room temperature.

[0049] The wind turbine hollow main shaft of this embodiment is obtained by a wind turbine hollow main shaft copying forging process.

[0050] The microstructure distribution of the wind turbine hollow main shaft is a composite structure of matrix phase + grain boundary distributed MnNi phase.

[0051] The wind power hollow main shaft of this embodiment is used in a wind turbine generator set.

[0052] A wind turbine generator set includes the wind turbine hollow main shaft of this embodiment.

[0053] As shown in FIG1 , the grain size of the wind turbine hollow main shaft of this embodiment is very fine, with a grain size of 5 to 30 microns, reaching level 7 or above.

[0054] The complex phase structure can also be seen from Figure 1, where the gray is the matrix phase, and the dots (position 2) and blocks (position 1) inside the grain boundary are MnNi phases, indicating that this embodiment obtains a complex phase structure of matrix phase + grain boundary distributed MnNi phase at room temperature.

[0055] The electron probe was performed on the point (position 2) and block (position 1) in Figure 1, and the data are shown in Table 1 below.

[0056] Table 1 Electron probe element analysis of the dot-shaped and block-shaped parts of Example 1

[0057] It can be seen that the MnNi phase at room temperature was obtained in this embodiment.

[0058] Example 2

[0059] A wind power hollow main shaft copy forging process, comprising the following steps:

[0060] S1, hot delivery billet: alloy elements are melted according to the formula and cast into ingots, and then hot delivery of the ingots; the hot delivery ingots are placed in an insulation barrel at 865°C after demoulding; the metal element components in the formula are as follows by mass percentage: C: 0.40%, Si: 0.20%, Mn: 1.50%, Ni: 1.65%, P: 0.01%, S: 0.01%, Cr: 1.05%, Mo: 0.25%, Cu: 0.05%, V: 0.08%, Sn: 0.001%, Sb: 0.0005%, and the balance is Fe; the mass ratio of Mn to Ni in the formula is: Mn:Ni = 1:1.1;

[0061] S2, drawing and upsetting: After heating the S1 hot-delivered steel ingot, it is subjected to the following steps: first drawing, first upsetting, second drawing, and second upsetting forging. Before forging, the hot-delivered steel ingot is heated to 1270°C at a heating rate of 75°C / h and kept at this temperature for 5.5h.

[0062] The primary drawing ratio is 6.3, the primary upsetting ratio is 7.0, the secondary drawing ratio is 3.45, and the secondary upsetting ratio is 3.9. The primary drawing-primary upsetting is completed at 1190°C, and the secondary drawing-secondary upsetting is completed at 1050°C.

[0063] S3, ingot punching: The S2 ingot is repeatedly stretched and upset, then remelted and heated for punching. The punch is punched downward twice, with the first punching temperature at 1165°C. The punching is stopped when the ingot reaches 2 / 3 of its depth. The ingot is then remelted and heated at 85°C / h to 1165°C. The forging is then turned 180° and placed for a second reverse punching until the ingot is punched through.

[0064] S4, drawing and rounding: The forgings after punching in S3 are returned to the furnace for heating and then subjected to shaft drawing and rounding; after being returned to the furnace and heated to 1210°C at 55°C / h, they are drawn. The drawing process is as follows: anvil width ratio of 0.7, reduction of 90mm, 90° clockwise rotation, and feed of 0.5 of the anvil width to obtain a drawn forging; the drawn forging is rounded. Before rounding, the drawn forgings are returned to the furnace for heating to 1210°C and then rounded. The rounding process is as follows: 850°C, anvil width ratio of 0.85, reduction of 15mm, and feed of 0.75 of the anvil width;

[0065] S5, controlled cooling after forging: the forging obtained in S4 is placed in an insulation barrel for slow cooling, and then air-cooled to room temperature to obtain a finished wind power hollow main shaft; the slow cooling rate in the insulation barrel is 7°C / h, and after slow cooling to 190°C, it is taken out and air-cooled to room temperature.

[0066] The wind turbine hollow main shaft of this embodiment is obtained by a wind turbine hollow main shaft copying forging process.

[0067] The microstructure distribution of the wind turbine hollow main shaft is a composite structure of matrix phase + grain boundary distributed MnNi phase.

[0068] The wind power hollow main shaft of this embodiment is used in a wind turbine generator set.

[0069] A wind turbine generator set includes the wind turbine hollow main shaft of this embodiment.

[0070] Example 3

[0071] A wind power hollow main shaft copy forging process, comprising the following steps:

[0072] S1, hot delivery billet: alloying elements are melted according to the formula and cast into ingots, which are then hot delivered; the hot delivered ingots are placed in an insulation barrel at 880°C after demoulding; the metal element composition in the formula is as follows by mass percentage: C: 0.42%, Si: 0.25%, Mn: 1.73%, Ni: 2.11%, P: 0.005%, S: 0.02%, Cr: 1.18%, Mo: 0.29%, Cu: 0.01%, V: 0.12%, Sn: 0.001%, Sb: 0.001%, and the balance is Fe; the mass ratio of Mn to Ni in the formula is: Mn:Ni = 1:1.22;

[0073] S2, drawing and upsetting: After heating the S1 hot-delivered steel ingot, it is subjected to the following steps: first drawing - first upsetting - second drawing - second upsetting forging; before forging, the hot-delivered steel ingot is heated to 1280°C at a heating rate of 80°C / h and kept at this temperature for 6 hours;

[0074] The first drawing ratio is 6.5, the first upsetting ratio is 7.2, the second drawing ratio is 3.6, and the second upsetting ratio is 4.1. The first drawing-first upsetting is completed at 1260℃, and the second drawing-second upsetting is completed at 1080℃.

[0075] S3, ingot punching: The S2 ingot is repeatedly stretched and upset, then returned to the furnace for heating and then punched. The punching is performed with a downward punch twice. The first punching temperature is 1180°C, and the punching is stopped when the ingot reaches 2 / 3 of its depth. The ingot is then returned to the furnace for heating at 90°C / h to 1180°C. The forging is then turned 180° and placed for a second reverse punching until the ingot is punched through.

[0076] S4, drawing and rounding: The forgings after punching in S3 are returned to the furnace for heating and then subjected to shaft drawing and rounding; after being returned to the furnace and heated to 1220°C at 60°C / h, they are drawn. The drawing process is as follows: anvil width ratio of 0.8, reduction of 100mm, 90° clockwise turning, and feed of 0.6 of the anvil width to obtain a drawn forging; the drawn forging is rounded. Before rounding, the drawn forging is returned to the furnace for heating to 1220°C and then rounded. The rounding process is as follows: 980°C, anvil width ratio of 0.9, reduction of 20mm, and feed of 0.8 of the anvil width;

[0077] S5, controlled cooling after forging: the forging obtained in S4 is placed in an insulation barrel for slow cooling, and then air-cooled to room temperature to obtain a finished wind power hollow main shaft; the slow cooling rate in the insulation barrel is 10℃ / h, and after slow cooling to 200℃, it is taken out and air-cooled to room temperature.

[0078] The wind turbine hollow main shaft of this embodiment is obtained by a wind turbine hollow main shaft copying forging process.

[0079] The microstructure distribution of the wind turbine hollow main shaft is a composite structure of matrix phase + grain boundary distributed MnNi phase.

[0080] The wind power hollow main shaft of this embodiment is used in a wind turbine generator set.

[0081] A wind turbine generator set includes the wind turbine hollow main shaft of this embodiment.

[0082] Comparative Example 1

[0083] A wind power hollow main shaft copy forging process, comprising the following steps:

[0084] S1, hot delivery billet: alloy elements are melted according to the formula and cast into ingots, and then the ingots are hot delivered; the hot delivery ingots are placed in an insulation barrel at 850°C after demoulding; the metal element composition in the formula is as follows by mass percentage: C: 0.36%, Si: 0.15%, Mn: 1.21%, Ni: 1.27%, P: 0.02%, S: 0.02%, Cr: 0.91%, Mo: 0.22%, Cu: 0.1%, V: 0.03%, Sn: 0.002%, Sb: 0.001%, and the balance is Fe; the mass ratio of Mn to Ni in the formula is: Mn:Ni = 1:1.05;

[0085] S2, drawing and upsetting: After heating the S1 hot-delivered steel ingot, it is subjected to the following steps: first drawing - first upsetting - second drawing - second upsetting forging; before forging, the hot-delivered steel ingot is heated to 1260°C at a heating rate of 70°C / h and kept at this temperature for 5h;

[0086] The first drawing ratio is 6.1, the first upsetting ratio is 6.7, the second drawing ratio is 3.3, and the second upsetting ratio is 3.8. The first drawing-first upsetting is completed at 1080℃, and the second drawing-second upsetting is completed at 980℃.

[0087] S3, ingot punching: The S2 ingot is repeatedly stretched and upset, then remelted and heated for punching. The punch is punched downward twice, with the first punching temperature at 1150°C. The punching is stopped when the ingot reaches 2 / 3 of its depth. The ingot is then remelted and heated at 80°C / h to 1150°C. The forging is then turned 180° and placed for a second reverse punching until the ingot is punched through.

[0088] S4, drawing and rounding: The forgings after punching in S3 are returned to the furnace for heating and then subjected to shaft drawing and rounding; after returning to the furnace and heating to 1200℃ at 50℃ / h, they are drawn. The drawing process is as follows: anvil width ratio of 0.6, reduction of 80mm, 90° clockwise turning, and feed of 0.4 of the anvil width to obtain a drawn forging; the drawn forging is rounded. Before rounding, the drawn forging is returned to the furnace for heating to 1200℃ and then rounded. The rounding process is as follows: anvil width ratio of 0.8, reduction of 10mm, and feed of 0.7 of the anvil width at 1000℃;

[0089] S5, controlled cooling after forging: the forging obtained in S4 is placed in an insulation barrel for slow cooling, and then air-cooled to room temperature to obtain a finished wind power hollow main shaft; the slow cooling rate in the insulation barrel is 5°C / h, and after slow cooling to 180°C, it is taken out and air-cooled to room temperature.

[0090] Comparative Example 2

[0091] A wind power hollow main shaft copy forging process, comprising the following steps:

[0092] S1, hot delivery billet: alloy elements are melted according to the formula and cast into ingots, and then the ingots are hot delivered; the hot delivery ingots are placed in an insulation barrel at 850°C after demoulding; the metal element composition in the formula is as follows by mass percentage: C: 0.36%, Si: 0.15%, Mn: 1.21%, Ni: 1.27%, P: 0.02%, S: 0.02%, Cr: 0.91%, Mo: 0.22%, Cu: 0.1%, V: 0.03%, Sn: 0.002%, Sb: 0.001%, and the balance is Fe; the mass ratio of Mn to Ni in the formula is: Mn:Ni = 1:1.05;

[0093] S2, drawing and upsetting: After heating the S1 hot-delivered steel ingot, it is subjected to the following steps: first drawing - first upsetting - second drawing - second upsetting forging; before forging, the hot-delivered steel ingot is heated to 1260°C at a heating rate of 70°C / h and kept at this temperature for 5h;

[0094] The primary drawing ratio is 6.1, the primary upsetting ratio is 6.7, the secondary drawing ratio is 6.0, and the secondary upsetting ratio is 6.5. The primary drawing-primary upsetting is completed at 1080°C. After the primary drawing-primary upsetting is completed, the steel ingot is heated to 1260°C at a heating rate of 70°C / h, and then the secondary drawing-secondary upsetting is carried out. The secondary drawing-secondary upsetting is completed at 1180°C.

[0095] S3, ingot punching: The S2 ingot is repeatedly stretched and upset, then remelted and heated for punching. The punch is punched downward twice, with the first punching temperature at 1150°C. The punching is stopped when the ingot reaches 2 / 3 of its depth. The ingot is then remelted and heated at 80°C / h to 1150°C. The forging is then turned 180° and placed for a second reverse punching until the ingot is punched through.

[0096] S4, drawing and rounding: The forgings after punching in S3 are returned to the furnace for heating and then subjected to shaft drawing and rounding; the forgings are heated to 1200°C at 50°C / h and then drawn. The drawing process is as follows: anvil width ratio of 0.6, reduction of 80mm, 90° clockwise turning, and feed of 0.4 of the anvil width to obtain a drawn forging; the drawn forgings are rounded. Before rounding, the drawn forgings are returned to the furnace for heating to 1200°C and then rounded. The rounding process is as follows: anvil width ratio of 0.8, reduction of 10mm, and feed of 0.7 of the anvil width at 700°C;

[0097] S5, controlled cooling after forging: the forging obtained in S4 is placed in an insulation barrel for slow cooling, and then air-cooled to room temperature to obtain a finished wind power hollow main shaft; the slow cooling rate in the insulation barrel is 5°C / h, and after slow cooling to 180°C, it is taken out and air-cooled to room temperature.

[0098] Comparative Example 3

[0099] A wind power hollow main shaft copy forging process, comprising the following steps:

[0100] S1, hot delivery billet: alloy elements are melted according to the formula and cast into ingots, and then the ingots are hot delivered; the hot delivery ingots are placed in an insulation barrel at 850°C after demoulding; the metal element composition in the formula is as follows by mass percentage: C: 0.36%, Si: 0.15%, Mn: 1.21%, Ni: 1.27%, P: 0.02%, S: 0.02%, Cr: 0.91%, Mo: 0.22%, Cu: 0.1%, V: 0.03%, Sn: 0.002%, Sb: 0.001%, and the balance is Fe; the mass ratio of Mn to Ni in the formula is: Mn:Ni = 1:1.05;

[0101] S2, drawing and upsetting: After heating the S1 hot-delivered steel ingot, it is subjected to the following steps: first drawing - first upsetting - second drawing - second upsetting forging; before forging, the hot-delivered steel ingot is heated to 1260°C at a heating rate of 70°C / h and kept at this temperature for 5h;

[0102] The primary drawing ratio is 5.0, the primary upsetting ratio is 5.5, the secondary drawing ratio is 3.3, and the secondary upsetting ratio is 3.8. The primary drawing-primary upsetting is completed at 960°C. After the primary drawing-primary upsetting is completed, the steel ingot is heated to 1260°C at a heating rate of 70°C / h, and then the secondary drawing-secondary upsetting is carried out. The secondary drawing-secondary upsetting is completed at 980°C.

[0103] S3, ingot punching: The S2 ingot is repeatedly stretched and upset, then remelted and heated for punching. The punch is punched downward twice, with the first punching temperature at 1150°C. The punching is stopped when the ingot reaches 2 / 3 of its depth. The ingot is then remelted and heated at 80°C / h to 1150°C. The forging is then turned 180° and placed for a second reverse punching until the ingot is punched through.

[0104] S4, drawing and rounding: The forgings after punching in S3 are returned to the furnace for heating and then subjected to shaft drawing and rounding; the forgings are heated to 1200°C at 50°C / h and then drawn. The drawing process is as follows: anvil width ratio of 0.6, reduction of 80mm, 90° clockwise turning, and feed of 0.4 of the anvil width to obtain a drawn forging; the drawn forgings are rounded. Before rounding, the drawn forgings are returned to the furnace for heating to 1200°C and then rounded. The rounding process is as follows: anvil width ratio of 0.8, reduction of 10mm, and feed of 0.7 of the anvil width at 700°C;

[0105] S5, controlled cooling after forging: the forging obtained in S4 is placed in an insulation barrel for slow cooling, and then air-cooled to room temperature to obtain a finished wind power hollow main shaft; the slow cooling rate in the insulation barrel is 5°C / h, and after slow cooling to 180°C, it is taken out and air-cooled to room temperature.

[0106] As shown in FIG2 , the microstructure diagram of the hollow spindles obtained in Comparative Examples 1 to 3 is shown. From FIG2 , it can be seen that the comparative examples only have matrix structure, the black lines are grain boundaries, there is no MnNi phase, and the grain size is 50 to 150 microns.

[0107] The black parts of Comparative Examples 1 to 3 were subjected to electron probe testing, and the data are shown in Table 2 below.

[0108] Table 2 Electron probe element analysis of the black part of the comparative example

[0109] It can be seen that the comparative example did not obtain the MnNi phase at room temperature, and thus could not improve the overall low-temperature toughness of the forging and could not enhance the low-temperature impact performance of the forging.

[0110] Table 3 below shows the performance comparison results.

[0111] The mechanical properties of the hollow spindles of Examples 1 to 3 and Comparative Examples 1 to 3 were tested, and the test results are as follows:

[0112] Table 3 Hollow spindle performance

[0113] It should be understood that in order to streamline the present disclosure and aid understanding of one or more of the various inventive aspects, in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together into a single embodiment, figure, or description thereof. However, this disclosed method should not be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as reflected in the claims, inventive aspects lie in less than all of the features of the previously disclosed embodiments. Accordingly, the claims that follow the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of the invention.

[0114] Although the present invention has been described with respect to a limited number of embodiments, it will be apparent to those skilled in the art, having benefit of the foregoing description, that other embodiments are contemplated within the scope of the invention thus described. Furthermore, it should be noted that the language used in this specification has been selected primarily for readability and didactic purposes, rather than for the purpose of explaining or limiting the subject matter of the present invention. Consequently, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the appended claims. The disclosure of the present invention is intended to be illustrative rather than restrictive of the scope of the invention, which is defined by the appended claims.

[0115] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A wind power hollow main shaft profiling forging process, characterized in that: The following steps are involved: S1, hot delivery of billets: melting alloy elements according to the formula and casting into ingots, and then hot delivery of steel ingots; the mass ratio of Mn and Ni in the formula is: Mn:Ni=1:(1.05-1.22); S2, drawing and upsetting: After heating the S1 hot-delivered steel ingot, it is subjected to primary drawing, primary upsetting, secondary drawing and secondary upsetting forging; before forging, the hot-delivered steel ingot is heated to 1260-1280°C at a heating rate of 70-80°C / h and kept warm for 5-6h; The primary drawing ratio is 6.1-6.5, the primary upsetting ratio is 6.7-7.2, the secondary drawing ratio is 3.3-3.6, and the secondary upsetting ratio is 3.8-4.1, wherein the primary drawing and primary upsetting are completed in the temperature range of 1080-1260°C, and the secondary drawing and secondary upsetting are completed in the temperature range of 980-1080°C; S3, ingot punching: the S2 ingot is repeatedly stretched and upset, and then returned to the furnace for heating and then punched; S4, drawing and rounding: the forgings after punching in S3 are returned to the furnace for heating and then the shaft body is drawn and rounded; the forgings are returned to the furnace for heating to 1200-1220°C at 50-60°C / h and then drawn, the drawing process is anvil width ratio of 0.6-0.8, the pressing amount is 80-100mm, 90° clockwise turning method, the feed amount is 0.4-0.6 of the anvil width, and the drawn forgings are obtained; the drawn forgings are rounded, and before rounding, the drawn forgings are returned to the furnace for heating to 1200-1220°C and then rounded, the rounding process is: 700-980°C, the anvil width ratio is 0.8-0.9, the pressing amount is 10-20mm, and the feed amount is 0.7-0.8 of the anvil width; S5, controlled cooling after forging: placing the forging obtained in S4 in a heat preservation barrel to slowly cool it, and then air-cooling it to room temperature to obtain the finished wind power hollow main shaft.

2. A wind power hollow main shaft copying forging process according to claim 1, characterized in that: The element components in the formula are calculated by mass percentage: C: 0.36% ~ 0.42%, Si: 0.15% ~ 0.25%, Mn: 1.21% ~ 1.73%, Ni: 1.27% ~ 2.11%, P: ≤0.02%, S: ≤0.02%, Cr: 0.91% ~ 1.18%, Mo: 0.22% ~ 0.29%, Cu: ≤0.1%, V: 0.03% ~ 0.12%, Sn≤0.002%, Sb≤0.001%, and the balance is Fe.

3. The process for forging a wind power hollow main shaft according to claim 1, characterized in that: In S1, the hot-delivered steel ingot is placed in a heat preservation barrel at 850-880° C. for hot-delivery after the steel ingot is demoulded.

4. The wind power hollow main shaft profiling forging process according to claim 1 is characterized in that: In S3, the punching is performed twice downwards with a punch head, the first punching temperature is 1150-1180°C, and the punching is stopped when the ingot is 2 / 3 deep. The forging is then returned to the furnace and heated to 1150-1180°C at 80-90°C / h. The forging is then turned 180° and placed for a second reverse punching until the ingot is punched through.

5. The wind power hollow main shaft copying forging process according to claim 1 is characterized in that: In S5, the slow cooling rate in the heat preservation barrel is 5-10°C / h, and after slow cooling to 180-200°C, the sample is taken out and air-cooled to room temperature.

6. A wind turbine hollow main shaft obtained by the wind turbine hollow main shaft copying forging process according to any one of claims 1 to 5.

7. The wind power hollow main shaft according to claim 6, characterized in that: The microstructure distribution of the wind turbine hollow main shaft is a complex phase structure of matrix phase and grain boundary distributed MnNi phase.

8. The wind power hollow main shaft according to claim 6, characterized in that: The tensile strength of the wind power hollow main shaft is 921-981MPa, the yield strength is 803-936MPa, the hardness is 336-391HB, and the -40℃ impact AKV / J is 105-109.

9. Application of the wind power hollow main shaft according to claim 6 in a wind power generator set.

10. A wind turbine generator set, characterized in that: It comprises the wind power hollow main shaft according to claim 6.

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