Forging method and forging device for ultra-large inner hole thin-wall wind power main shaft

Abstract

The invention discloses a forging method and a forging device for a thin-wall wind power main shaft with an ultra-large inner hole, and belongs to the technical field of wind power main shaft manufacturing. The invention discloses a forging method for a thin-wall wind power main shaft with an ultra-large inner hole. The forging method comprises the following steps that firstly, chamfering, water gap removing, upsetting and drawing-out are conducted, and then blanking is conducted; step 2, upsetting to a certain height by using an upsetting drain plate, punching, chambering by using a saddle, coining and distributing; thirdly, shaft bodies are formed and subjected to heat preservation, all shafts in the middle are drawn out to the process size through a profiling core rod, and finally the two small shafts are reserved in advance for hole shrinkage; fourthly, the inner hole of the small shaft end is shrunk to the process size, the flange is upset to the process size through a special tool, and finishing is conducted; by means of the profiling core rod, the shaft hole can be conveniently machined, the follow-up machining time is shortened, waste of workpieces can be reduced, the nozzles are arranged on the inner wall of the protection plate, the working face of the anvil block can be purged in the forging process, gathering of oxidized chippings on the anvil block is reduced, and the forging efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of manufacturing wind power spindle, and in particular to a forging method and forging device for an extra-large inner hole thin-walled wind power spindle. Background Art

[0002] Under the background of global energy conservation and emission reduction, reducing the dependence on fossil energy and increasing the use of solar energy and wind energy have become the consensus of countries around the world. China has excellent wind resources and rich potential exploitable resources. As a new type of clean energy, wind power generation has become the focus of national attention and development, and has developed extremely rapidly. The wind power spindle is an important component in the wind turbine, which is used to connect the blade hub and the gearbox and play a role in transmitting kinetic energy. During the production and processing process, a forging machine is often used for forging.

[0003] At present, forging is basically solid forging, and the inner hole is completed by subsequent machining. However, as the spindle size continues to increase, more and more material is removed during the machining of the inner hole, which not only leads to a longer machining time, but also wastes materials. And during the forging process, there will be oxidation debris on the forging. When the oxidation debris falls on the anvil and the forging continues to be die-forged, the accumulated oxidation debris adheres to the forging again, affecting the forging effect of the forging, thereby increasing the workload of the staff and reducing the forging efficiency of the forging. Summary of the Invention

[0004] The purpose of the present invention is to solve the problems in the prior art that when machining the inner hole, not only the machining time will be increased, but also material waste will occur, and during forging, the oxidation debris on the forging accumulates on the anvil, affecting the forging effect of the forging, and to propose a forging method and forging device for an extra-large inner hole thin-walled wind power spindle.

[0005] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0006] A forging method for an extra-large inner hole thin-walled wind power spindle includes the following steps:

[0007] Step 1: Heat the forging to 1200 - 1250 °C, keep it warm, then chamfer, remove the sprue, upset, draw out and cut the material.

[0008] Step 2: Heat to 1200 - 1250 °C, keep it warm, upset to a certain height with an upsetting punch, punch holes, expand the holes with a mandrel, emboss, and distribute the material.

[0009] Step 3: Shape the shaft body, heat to 1200 - 1250 °C, keep it warm, use a profiling mandrel to draw out the middle shafts to the process dimensions, and finally leave a pre-set allowance for the two small shafts for hole closing.

[0010] Step 4: Heat to 1150 - 1250 °C, keep warm, shrink the inner hole at the small shaft end to the process dimension, upset the flange to the process dimension using a special tooling, and finish.

[0011] An ultra-large inner hole thin-walled wind power spindle forging device, including a forging machine with a hydraulic lifting part, an anvil is arranged on the forging machine, and further includes: a protective plate with an arc-shaped structure, arranged on the forging machine, the anvil is located inside the protective plate, and a plurality of nozzles for purging the top end face of the anvil are fixedly arranged on the inner wall of the protective plate, and a gas supply part for supplying gas to the nozzles is arranged inside the protective plate; a receiving tray with an annular structure, sleeved on the anvil, the inner wall and the outer wall of the receiving tray are respectively abutted against the side wall of the anvil and the inner wall of the protective plate, and the receiving tray is connected with the bottom of the protective plate through a guide rod for lifting.

[0012] Preferably, in order to facilitate the supply of gas to the nozzles, the gas supply part includes an upper shield arranged to lift inside the protective plate, a piston cavity is opened inside the protective plate, a piston plate is arranged to lift inside the piston cavity, one end of the upper shield extending into the piston cavity is fixedly connected with the piston plate, and an air outlet pipe is opened inside the protective plate, an air inlet pipe is opened on the upper shield, one ends of the air outlet pipe and the air inlet pipe are both communicated with the inside of the piston cavity, the other end of the air outlet pipe is communicated with the nozzle, and one-way valves are fixedly arranged on both the air outlet pipe and the air inlet pipe.

[0013] Further, in order to facilitate the lifting of the fixing seat with the upper shield, an arc-shaped strong magnet is fixedly arranged on the top of the upper shield, a fixing seat is arranged to lift on the forging machine, the top of the fixing seat is fixedly connected with the output end of the hydraulic lifting part, and a forging head is fixedly arranged at the bottom of the fixing seat through bolts, and the strong magnet is magnetically attracted to the bottom end face of the fixing seat.

[0014] Further, in order to heat other components inside the piston cavity, a heating cavity is opened inside the protective plate, the bottom of the piston cavity is communicated with the inside of the heating cavity, one end of the air outlet pipe is communicated with the inside of the heating cavity, and a heating wire is fixedly arranged inside the heating cavity.

[0015] Further, a first pipe and a second pipe are opened inside the fixing seat, a channel with a planar spiral structure is opened inside the forging head, one end of the channel is communicated with the first pipe, the other end of the channel is communicated with one end of the second pipe, and an annular hole is opened inside the fixing seat, the other end of the second pipe is communicated with the annular hole, the other end of the air inlet pipe is communicated with the annular hole, and the channel is opened near the forging end of the forging head.

[0016] Furthermore, a lifting hole is opened inside the protective plate, the bottom of the lifting hole is communicated with the heating cavity, a sealing column is arranged to lift inside the lifting hole, and one end of the guide rod extending into the lifting hole is fixedly connected with the sealing column.

[0017] Further, a spring is sleeved on the guide rod, and two ends of the spring respectively abut against the protection plate and the material receiving tray, and multiple groups of the guide rods and the sealing columns are correspondingly arranged.

[0018] Preferably, avoidance grooves are formed in both the protection plate and the upper shield, and a discharge plate is fixedly arranged on the material receiving tray, and the discharge plate extends out of the forging machine from the avoidance groove.

[0019] Further, multiple groups of diversion grooves are formed in the inner wall of the protection plate, the top end face of the material receiving tray is inclined, and an inclined surface inclined towards the top of the material receiving tray is fixedly arranged at the bottom of the diversion groove.

[0020] Compared with the prior art, the present invention provides a forging method and a forging device for an extra-large inner hole thin-wall type wind power main shaft, and has the following beneficial effects:

[0021] 1. For the forging method of the extra-large inner hole thin-wall type wind power main shaft, by using a profiling mandrel during the processing, it is not only convenient to process the hole in the shaft, reduce the subsequent machining time, but also can reduce the waste of workpieces, greatly improve the utilization rate of raw materials, and improve the forging effect;

[0022] 2. For the forging device of the extra-large inner hole thin-wall type wind power main shaft, by arranging a protection plate with an arc-shaped structure on the outer wall of the anvil block, on the one hand, a nozzle is fixedly arranged on the inner wall of the protection plate, which can blow the working surface of the anvil block during forging, reduce the accumulation of oxidation debris on the anvil block, and reduce the amount of debris adhering to the forging, thereby helping to reduce the forging duration. On the other hand, through the arc-shaped protection plate, the forging area can be approximately surrounded, which not only has a certain heat preservation effect on the forging, increases the single forging duration, but also can reduce the splashing of debris in all directions and improve the processing safety;

[0023] 3. For the forging device of the extra-large inner hole thin-wall type wind power main shaft, by arranging a material receiving tray between the protection plate and the anvil block, the oxidation debris can be collected, the subsequent cleaning difficulty can be reduced, and a discharge plate is fixedly arranged on the material receiving tray. The top end faces of the material receiving tray and the discharge plate are both inclined, and the material receiving tray can elastically lift and lower, and can automatically discharge the debris through the discharge plate, improving the use effect;

[0024] 4. The forging device for the super-large inner-hole thin-wall wind power spindle has a lifting hole formed in the protective plate, a sealing column arranged in the lifting hole, and a spring sleeved on the guiding rod. On the one hand, the vibration generated during forging can cause the material receiving tray to move up and down. This not only facilitates the discharge of debris from the material receiving tray but also, during the lifting process, drives the sealing column to slide up and down in the lifting hole. At this time, it can have a certain impact on the gas in the heating chamber, helping to make the gas in the heating chamber and the gas in the piston chamber move, improving the uniformity of gas heating. On the other hand, during the lifting process of the piston plate, when the piston plate slides downward, the pressure in the piston chamber increases. At this time, the sealing column can drive the material receiving tray to rise through the guiding rod. Conversely, it can drive the material receiving tray to descend, causing the material receiving tray to move up and down repeatedly, improving the discharging effect of the material receiving tray.

[0025] For the parts not involved in this device, they are the same as the existing technology or can be implemented using the existing technology. In the process of processing, by using a profiling mandrel in the present invention, it is not only convenient to process the holes inside the shaft, reducing the subsequent machining time, but also can reduce the waste of workpieces, greatly improving the utilization rate of raw materials and the forging effect. A nozzle is fixedly arranged on the inner wall of the protective plate, which can blow the working surface of the anvil during forging, reducing the accumulation of oxidation debris on the anvil and the amount of debris adhering to the forgings, improving the forging efficiency. Brief Description of the Drawings

[0026] Figure 1 It is a schematic structural diagram of a forging device for a super-large inner-hole thin-wall wind power spindle proposed by the present invention;

[0027] Figure 2 It is a sectional view of a forging device for a super-large inner-hole thin-wall wind power spindle proposed by the present invention;

[0028] Figure 3 It is a schematic structural diagram of the protective plate of a forging device for a super-large inner-hole thin-wall wind power spindle proposed by the present invention;

[0029] Figure 4 It is a partial view of a forging device for a super-large inner-hole thin-wall wind power spindle proposed by the present invention;

[0030] Figure 5 It is a forging device for a super-large inner-hole thin-wall wind power spindle proposed by the present invention Figure 4 The enlarged view of part A in it;

[0031] Figure 6 It is a forging device for a super-large inner-hole thin-wall wind power spindle proposed by the present invention Figure 4 The enlarged view of part B in it;

[0032] Figure 7 It is a forging device for a super-large inner-hole thin-wall wind power spindle proposed by the present inventionFigure 4 Enlarged view of part C;

[0033] Figure 8 An forging device for super-large inner-hole thin-walled wind power spindle proposed by the present invention Figure 4 Enlarged view of part D.

[0034] In the figure: 1, forging machine; 101, anvil block; 102, hydraulic lifting part; 2, protective plate; 201, piston cavity; 202, heating cavity; 203, annular groove; 204, nozzle; 205, lifting hole; 206, diversion groove; 207, air outlet pipe; 3, upper shield; 301, piston plate; 302, strong magnet; 303, air inlet pipe; 4, receiving tray; 401, discharge plate; 402, spring; 403, guide rod; 404, sealing column; 5, fixed seat; 501, first pipeline; 502, second pipeline; 503, annular hole; 6, forging head; 601, channel. Specific implementation mode

[0035] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0036] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0037] Embodiment:

[0038] A forging method for super-large inner-hole thin-walled wind power spindle includes the following steps:

[0039] Step 1: Heat the forging to 1200 - 1250 °C, keep it warm, and then chamfer, remove the sprue, upset, and cut the material after drawing out.

[0040] During use, by heating the forging to the corresponding temperature, keeping it warm for a certain time, then chamfering, removing the water inlet, and upsetting, the forging is drawn out and then cut.

[0041] Step 2: Heat to 1200 - 1250 °C, keep it warm, upset to a certain height with an upsetting punch, punch holes, expand the holes with a mandrel, emboss, and divide the materials.

[0042] After the above operations are completed, reheat and hold the forging, then upset it to a certain height using an upsetting die, and then perform punching, expanding the hole with a mandrel, embossing, and dividing the material.

[0043] Step 3: Shaft body forming. Heat to 1200 - 1250 °C, hold the temperature, and draw out the intermediate shafts to the process dimensions using a profiling mandrel. Leave a pre-set allowance for the last two small shafts for hole closing.

[0044] When punching, use a profiling mandrel to reprocess the hole in the shaft. During the processing, using the profiling mandrel not only facilitates the processing of the hole in the shaft, reduces the subsequent machining time, but also reduces the waste of workpieces, greatly improves the utilization rate of raw materials, and enhances the forging effect.

[0045] Step 4: Heat to 1150 - 1250 °C, hold the temperature, shrink the inner hole of the small shaft end to the process dimensions, upset the flange to the process dimensions using a special tooling, and finish.

[0046] After machining the shaft hole, use a special tooling to upset the flange until it is machined to the process dimensions. The machining is convenient, and the utilization rate of raw materials is greatly improved. By using a profiling mandrel to machine the inner hole of the shaft, it helps to reduce the tonnage of the forged ingot, reduces the machining allowance at the inner hole part of the fan shaft, saves machining man-hours, and greatly reduces the weight of raw materials and the process machining time.

[0047] Refer to Figures 1 - 8, A forging device for an extra-large inner-hole thin-wall wind power spindle, including a forging machine 1 with a hydraulic lifting part 102. The hydraulic lifting part 102 generally preferably uses a hydraulic cylinder. An anvil 101 is arranged on the forging machine 1. The anvil 101 is generally directly placed on the working table of the forging machine 1 or fixed to the working table with bolts. Here, we preferably fix the anvil 101 to the working table with bolts. It also includes: a protective plate 2 in an arc structure, arranged on the forging machine 1. A base is fixedly arranged on the outer wall of the protective plate 2 and fixed to the working table with bolts. Moreover, the anvil 101 is located inside the protective plate 2, and the axis of the anvil 101 coincides with the axis of the protective plate 2. And a plurality of groups of nozzles 204 for purging the top end face of the anvil 101 are fixedly arranged on the inner wall of the protective plate 2. The number of nozzles 204 is set from two groups to ten groups. Here, we preferably choose six groups. A gas supply part for supplying gas to the nozzles 204 is arranged inside the protective plate 2. During use, during the forging process, the gas supply part supplies gas to the nozzles 204, and the nozzles 204 can blow away the oxidized debris falling on the anvil 101 from the forgings, reducing the accumulation on the anvil 101 and decreasing the amount of oxidized debris adhering to the forgings, thereby helping to reduce the forging duration, improving the processing effect, and also facilitating the subsequent cleaning of the debris and enhancing the use effect; a receiving tray 4 in a ring structure, sleeved on the anvil 101. The inner wall and the outer wall of the receiving tray 4 are respectively abutted against the side wall of the anvil 101 and the inner wall of the protective plate 2. That is to say, the inner ring of the receiving tray 4 is abutted against the outer wall of the anvil 101, and the outer wall of the receiving tray 4 is abutted against the inner wall of the protective plate 2. And the receiving tray 4 is connected to the bottom of the protective plate 2 through a guide rod 403 for lifting. During use, by arranging the receiving tray 4 between the protective plate 2 and the anvil 101, the falling oxidized debris can be collected, reducing the subsequent cleaning difficulty and improving the use effect.

[0048] During use, by arranging the protective plate 2 in an arc structure on the outer wall of the anvil 101, on the one hand, the nozzles 204 are fixedly arranged on the inner wall of the protective plate 2, which can purge the working surface of the anvil 101 during the forging process, reducing the accumulation of oxidized debris on the anvil 101 and decreasing the amount of debris adhering to the forgings, thereby helping to reduce the forging duration. On the other hand, through the arc-structured protective plate 2, the forging area can be approximately surrounded. It not only has a certain heat preservation effect on the forgings, increasing the single forging duration, but also can reduce the splashing of debris in all directions, improving the processing safety; by arranging the receiving tray 4 between the protective plate 2 and the anvil 101, the oxidized debris can be collected, reducing the subsequent cleaning difficulty. And a discharge plate 401 is fixedly arranged on the receiving tray 4. The top end faces of the receiving tray 4 and the discharge plate 401 are both inclined. The receiving tray 4 can elastically lift and automatically discharge the debris through the discharge plate 401, improving the use effect.

[0049] Refer to Figure 2 and Figure 4, the air supply part can use an air pump or a blower to supply air to the nozzle 204. Here, we design the air supply part such that an upper baffle 3 is arranged to be lifted and lowered within the protective plate 2. A piston chamber 201 is formed within the protective plate 2, and a piston plate 301 is arranged to be lifted and lowered within the piston chamber 201. One end of the upper baffle 3 extending into the piston chamber 201 is fixedly connected to the piston plate 301. An air outlet pipe 207 is formed within the protective plate 2, and an air inlet pipe 303 is formed on the upper baffle 3. One ends of both the air outlet pipe 207 and the air inlet pipe 303 are connected to the inside of the piston chamber 201, and the other end of the air outlet pipe 207 is connected to the nozzle 204. Here, an annular groove 203 is formed within the protective plate 2, and multiple groups of nozzles 204 are all connected to the annular groove 203. At this time, the other end of the air outlet pipe 207 is connected to the annular groove 203. Check valves are fixedly arranged on both the air outlet pipe 207 and the air inlet pipe 303. During use, the piston plate 301 is driven by the upper baffle 3 to lift and lower within the piston chamber 201. When descending, air can be pressed into the nozzle 204 through the air outlet pipe 207 to blow the anvil 101. When the upper baffle 3 rises, gas can be drawn from the outside through the air inlet pipe 303 for the next use. Moreover, arranging the upper baffle 3 on the protective plate 2 can enhance the heat preservation and protection effects.

[0050] Refer to Figure 4 and Figure 5 , a strong magnet 302 with an arc-shaped structure is fixedly arranged on the top of the upper baffle 3. A fixing seat 5 is arranged to be lifted and lowered on the forging machine 1. The top of the fixing seat 5 is fixedly connected to the output end of the hydraulic lifting part 102, and a forging head 6 is fixedly arranged at the bottom of the fixing seat 5 through bolts. The strong magnet 302 is magnetically attracted to the bottom end face of the fixing seat 5. During use, by magnetically attracting the upper baffle 3 to the bottom of the fixing seat 5 with the strong magnet 302, when the fixing seat 5 drives the forging head 6 to lift and lower for forging, the fixing seat 5 can simultaneously drive the upper baffle 3 to lift and lower, realizing air extraction and exhaust from the piston chamber 201 and improving the use effect.

[0051] Refer to Figure 4 , a heating chamber 202 is formed within the protective plate 2. The bottom of the piston chamber 201 is connected to the inside of the heating chamber 202, and one end of the air outlet pipe 207 is connected to the inside of the heating chamber 202. A heating wire is fixedly arranged within the heating chamber 202. The heating wire is preferably electrically heated. During use, by forming the heating chamber 202 within the protective plate 2 and fixedly arranging the heating wire within the heating chamber 202, the air within the heating chamber 202 and the piston chamber 201 can be heated, enabling the gas ejected from the nozzle 204 to have a certain temperature, reducing the impact on the surface temperature of the forging, and improving the use effect.

[0052] Refer to Figure 4 and Figure 5, a first pipe 501 and a second pipe 502 are provided in the fixed seat 5. A filter screen is fixedly provided at one end of the first pipe 501 away from the passage 601, which can reduce the inhaled dust. A passage 601 in a planar spiral structure is provided in the forging head 6. One end of the passage 601 is communicated with the first pipe 501, the other end of the passage 601 is communicated with one end of the second pipe 502, and an annular hole 503 is provided in the fixed seat 5. The other end of the second pipe 502 is communicated with the annular hole 503, and the other end of the air inlet pipe 303 is communicated with the annular hole 503. By providing the annular hole 503 in the fixed seat 5, it is convenient to supply gas to multiple groups of air inlet pipes 303 at the same time. The passage 601 is provided near the forging end of the forging head 6. During use, by providing the passage 601 in a planar spiral structure in the forging head 6, the forging head 6 can be cooled during the air intake process, preventing the temperature of the forging head 6 from rising after long-term use and causing deformation, and improving the service life of the forging head 6. Moreover, the temperature in the forging head 6 can preheat the gas entering the piston chamber 201, improving the heating effect on the air in the piston chamber 201.

[0053] Refer to Figure 4 and Figure 8 , a lifting hole 205 is provided in the protection plate 2. The bottom of the lifting hole 205 is communicated with the heating chamber 202, and a sealing column 404 is provided in the lifting hole 205 in a lifting manner. One end of the guide rod 403 extending into the lifting hole 205 is fixedly connected to the sealing column 404. A spring 402 is sleeved on the guide rod 403. The two ends of the spring 402 are respectively abutted against the protection plate 2 and the material receiving tray 4. And multiple groups of guide rods 403 and sealing columns 404 are correspondingly provided. The guide rods 403 and the sealing columns 404 are provided in two to ten groups, preferably four groups. During use, by providing the lifting hole 205 in the protection plate 2, the sealing column 404 is provided in the lifting hole 205, and the spring 402 is sleeved on the guide rod 403. On the one hand, the vibration generated by forging can make the material receiving tray 4 move up and down. This not only facilitates the discharge of debris from the material receiving tray 4, but also drives the sealing column 404 to slide up and down in the lifting hole 205 during the lifting process. At this time, it can have a certain impact on the gas in the heating chamber 202, helping to make the gas in the heating chamber 202 and the gas in the piston chamber 201 move, improving the uniformity of gas heating. On the other hand, during the lifting process of the piston plate 301, when the piston plate 301 slides downward, the pressure in the piston chamber 201 increases. At this time, the sealing column 404 can drive the material receiving tray 4 to rise through the guide rod 403. Conversely, it can drive the material receiving tray 4 to descend, making the material receiving tray 4 move up and down reciprocally, improving the discharging effect of the material receiving tray 4.

[0054] Refer to Figures 1 - 4, avoidance grooves are provided on both the protective plate 2 and the upper shield 3, facilitating the manipulation of forgings using a forklift. A discharge plate 401 is fixedly arranged on the material receiving tray 4, and the discharge plate 401 extends out of the forging machine 1 from the avoidance groove. During use, by fixedly arranging the discharge plate 401 on the material receiving tray 4, it is convenient for the debris on the material receiving tray 4 to be discharged, improving the use effect.

[0055] Referring to Figures 1 - 3 , a plurality of flow guiding grooves 206 are provided on the inner wall of the protective plate 2. The number of the flow guiding grooves 206 is two to ten groups, preferably eight groups. Moreover, the top end face of the material receiving tray 4 is inclined. An inclined surface inclined towards the top of the material receiving tray 4 is fixedly arranged at the bottom of the flow guiding groove 206. During use, by providing the flow guiding grooves 206 on the inner wall of the protective plate 2, when the fixed seat 5 slides downward, the air inside the protective plate 2 can be appropriately pushed downward. At this time, a part of the gas flows downward along the flow guiding grooves 206, having a certain purging effect on the top of the material receiving tray 4, accelerating the outward discharge of the debris on the material receiving tray 4, and improving the use effect.

[0056] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, making equivalent substitutions or changes, shall be covered by the protection scope of the present invention.

Claims

1. A forging method for a wind power spindle with an extra-large inner hole and thin wall, characterized in that It includes the following steps: Step 1: Heat the forging to 1200 - 1250 °C, keep it warm, then chamfer, remove the sprue, upset, draw out and cut the material. Step 2: Heat to 1200 - 1250 °C, keep it warm, upset to a certain height with an upsetting punch, punch holes, expand the holes with a mandrel, emboss, and divide the material. Step 3: Form the shaft body, heat to 1200 - 1250 °C, keep it warm, draw out the intermediate shafts to the process dimensions with a profiling mandrel, and finally leave a margin for the last two small shafts for hole closing. Step 4: Heat to 1150 - 1250 °C, keep it warm, shrink the inner hole of the small shaft end to the process dimensions, upset the flange to the process dimensions with a special tooling, and finish.

2. A forging device adopting the forging method of an extra-large inner-hole thin-wall type wind power spindle as described in claim 1, comprising a forging machine (1) with a hydraulic lifting part (102), wherein an anvil block (101) is arranged on the forging machine (1), and is characterized in that, It also includes: A protective plate (2) in an arc structure, which is arranged on the forging machine (1), the anvil block (101) is located inside the protective plate (2), and a plurality of groups of nozzles (204) for purging the top end face of the anvil block (101) are fixedly arranged on the inner wall of the protective plate (2), and an air supply part for supplying air to the nozzles (204) is arranged inside the protective plate (2). A material receiving tray (4) in a ring structure, which is sleeved on the anvil block (101), the inner wall and the outer wall of the material receiving tray (4) are respectively abutted against the side wall of the anvil block (101) and the inner wall of the protective plate (2), and the material receiving tray (4) is connected with the bottom of the protective plate (2) through a guide rod (403) for lifting.

3. The forging device for an extra-large inner-hole thin-wall type wind power spindle according to claim 2, wherein The air supply part includes an upper cover (3) arranged in the protective plate (2) in a lifting manner, a piston chamber (201) is opened in the protective plate (2), a piston plate (301) is arranged in the piston chamber (201) in a lifting manner, one end of the upper cover (3) extending into the piston chamber (201) is fixedly connected with the piston plate (301), and an air outlet pipe (207) is opened in the protective plate (2), an air inlet pipe (303) is opened on the upper cover (3), one ends of the air outlet pipe (207) and the air inlet pipe (303) are both communicated with the inside of the piston chamber (201), the other end of the air outlet pipe (207) is communicated with the nozzle (204), and one-way valves are fixedly arranged on both the air outlet pipe (207) and the air inlet pipe (303).

4. An oversized inner hole thin-walled wind power spindle forging device according to claim 3, characterized in that, An arc-shaped strong magnet (302) is fixedly arranged on the top of the upper cover (3), a fixed seat (5) is arranged in a lifting manner on the forging machine (1), the top of the fixed seat (5) is fixedly connected with the output end of the hydraulic lifting part (102), and a forging head (6) is fixedly arranged at the bottom of the fixed seat (5) through bolts, and the strong magnet (302) is magnetically attracted to the bottom end face of the fixed seat (5).

5. An ultra-large inner-hole thin-wall wind power spindle forging device according to claim 4, characterized in that, A heating chamber (202) is opened in the protective plate (2), the bottom of the piston chamber (201) is communicated with the inside of the heating chamber (202), one end of the air outlet pipe (207) is communicated with the inside of the heating chamber (202), and a heating wire is fixedly arranged inside the heating chamber (202).

6. An ultra-large inner hole thin-wall type wind power spindle forging device according to claim 5, characterized in that, A first pipe (501) and a second pipe (502) are formed in the fixed seat (5). A channel (601) with a planar spiral structure is formed in the forging head (6). One end of the channel (601) communicates with the first pipe (501), and the other end of the channel (601) communicates with one end of the second pipe (502). An annular hole (503) is formed in the fixed seat (5), and the other end of the second pipe (502) communicates with the annular hole (503). The other end of the air inlet pipe (303) communicates with the annular hole (503). The channel (601) is formed near the forging end of the forging head (6).

7. An oversized inner hole thin-walled wind power spindle forging device according to claim 6, characterized in that, A lifting hole (205) is formed in the protective plate (2). The bottom of the lifting hole (205) communicates with the heating cavity (202). A sealing column (404) is arranged to be liftable in the lifting hole (205). One end of the guide rod (403) extending into the lifting hole (205) is fixedly connected to the sealing column (404).

8. An oversized inner hole thin-walled wind power spindle forging device according to claim 7, characterized in that A spring (402) is sleeved on the guide rod (403). Two ends of the spring (402) are respectively abutted against the protective plate (2) and the material receiving tray (4). The guide rod (403) and the sealing column (404) are respectively arranged in multiple groups correspondingly.

9. The forging device for an extra-large inner-hole thin-wall type wind power spindle according to claim 2, characterized in that, Avoidance grooves are formed in both the protective plate (2) and the upper shield (3). A discharge plate (401) is fixedly arranged on the material receiving tray (4). The discharge plate (401) extends out of the forging machine (1) from the avoidance groove.

10. An oversized inner hole thin-walled wind power spindle forging device according to claim 9, characterized in that, Multiple groups of diversion grooves (206) are formed in the inner wall of the protective plate (2). The top end face of the material receiving tray (4) is inclined. An inclined surface inclined towards the top of the material receiving tray (4) is fixedly arranged at the bottom of the diversion groove (206).

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