A method for adjusting the misalignment of bolt holes in fan blades in the air

Abstract

The present invention relates to the field of wind power technology and discloses a method for adjusting the misalignment of wind turbine blade bolt holes mid-air. During the replacement of the bolts connecting the wind turbine blades to the hub, hydraulic nuts and dowel pins are used as intermediate connectors to achieve mid-air adjustment. This method addresses existing issues such as high removal costs for large components, low replacement efficiency, and significant safety risks.

Description

Technical Field

[0001] The invention relates to the technical field of wind power, in particular to an aerial adjustment method for the misalignment of bolt holes in wind turbine blades. Background Art

[0002] A wind farm project is located at an altitude of 3,130 to 3,600 meters. The wind farm is located in a high-altitude mountainous area, covering a total area of ​​approximately 35 square kilometers. The project has a capacity of 100,000 kilowatts, with 17 2,000-kilowatt turbines installed. During an inspection, wind farm operations and maintenance personnel discovered broken bolts connecting the turbine blades to the hub. The operations and maintenance center immediately organized personnel to replace the bolts. However, they discovered severe misalignment in the bolts, preventing proper replacement. Bearing misalignment required adjustment before reinstallation. Existing technologies for this purpose suffer from high costs associated with removing large components from the shelves, low replacement efficiency, and significant safety risks. Summary of the Invention

[0003] In order to overcome the shortcomings of the existing technology, the present invention provides a method for adjusting the misalignment of fan blade bolt holes in the air, which solves the problems of high cost of removing large components from the shelf, low replacement efficiency, and high safety risks in the existing technology.

[0004] The technical solution adopted by the present invention to solve the above problems is:

[0005] A method for adjusting the misalignment of fan blade bolt holes in mid-air utilizes hydraulic nuts and positioning pins as intermediate connecting parts during the process of replacing the connecting bolts between the fan blade and the hub, thereby achieving misalignment in mid-air adjustment.

[0006] As a preferred technical solution, the following steps are included:

[0007] H, remove M nuts at four locations on the blade; where M ≥ 2;

[0008] I. Install the hydraulic nut in the corresponding position of the nut removed in step A and apply the rated pressure;

[0009] J, remove N bolts from the blade and insert locating pins into the bolt holes corresponding to the N bolts removed; where 1≤N<M;

[0010] K, pitch the blades so that the locating pins enter the bolt holes until the end faces of the hexagonal heads of the locating pins are flush with the end faces of the bolts, thus completing the misalignment correction;

[0011] L. After the misalignment correction is completed, retighten all bolts and remove the positioning pins;

[0012] M, apply pre-tightening force after all bolts are installed;

[0013] N, remove the hydraulic nuts from the vacancies where the nuts were removed in step A. Install a new bolt for each hydraulic nut removed, and at the same time install the bolts inserted into the locating pins.

[0014] As a preferred technical solution, the following steps are also included after step G:

[0015] H. Apply thread locker evenly to the threaded ends of the new bolts.

[0016] As a preferred technical solution, in step H, the length of the thread fastener applied exceeds 1 / 2 of the thread length.

[0017] As a preferred technical solution, in step H, the thread fastener needs to be cured for 2 hours before the pre-tightening force is applied.

[0018] As a preferred technical solution, the following steps are also included after step H:

[0019] I. Install the O-ring on the un-adhesive end of the new bolt.

[0020] As a preferred technical solution, in step I, the O-ring is 160 mm to 170 mm away from the end face of the bolt.

[0021] As a preferred technical solution, the method further includes the following steps after step 1:

[0022] J. Use an Allen wrench to screw in the side of the new bolt that has been coated with fastener in a clockwise direction. Use a tape measure to measure the length of the bolt extending from the end face of the pitch bearing, ensuring that the length of the bolt extending from the adjacent bolt is ±2mm.

[0023] As a preferred technical solution, in step F, the preload force is gradually increased three times.

[0024] As a preferred technical solution, the method further includes the following steps before step A:

[0025] O, adjust the dislocated blades to the vertical blade downward position, manually change the pitch to make the wind wheel rotate freely, and ensure that the blades to be adjusted are in the vertical downward position. After the blades are vertically downward, retract the blades.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The present invention effectively solves the problem of misalignment of blade bolt holes without removing large components from the rack, thereby saving costs.

[0028] (2) The present invention effectively solves the problem of long fan downtime. It takes about 3 hours to process a single blade in the air, which greatly improves efficiency.

[0029] (3) The present invention effectively reduces the safety risks of on-site construction and ensures the safety of personnel and equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic diagram showing the state of adjusting the misaligned blades to the vertical blade downward position;

[0031] Figure 2 Schematic diagram of bolt position distribution;

[0032] Figure 3 This is the installation diagram of the positioning pin;

[0033] Figure 4 This is the manual hydraulic nut pipeline connection diagram. DETAILED DESCRIPTION

[0034] The present invention will be further described in detail below with reference to the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0035] Example 1

[0036] like Figures 1 to 4 As shown, the present invention is implemented by the following steps:

[0037] Manually shut down the fan → adjust the dislocated blades to the vertical downward position → remove the eight diagonal nuts → install the hydraulic nuts and apply rated pressure → remove the four bolts → loosen all nuts → adjust the blade separation → eliminate the dislocation → recycle the blades → tighten all nuts → disassemble and install the blade bolts → remove the locating pins → apply sealant → clean up the site → restore the unit.

[0038] More specifically, as follows:

[0039] 3.1 Manual shutdown of the fan

[0040] Prepare for manual shutdown of the wind turbine on site, hoist the tools required for adjustment into the nacelle, and place them in a safe location.

[0041] 3.2 Adjust the offset blades to the vertical blade downward position

[0042] Make the wind rotor rotate slowly and freely by manually changing the pitch, and ensure that the blades to be adjusted are in the vertical downward position (as shown in the figure below). After the blades are vertically downward, retract the blades and lock the hydraulic brake and mechanical locking pin in the braking state.

[0043] 3.3 First, keep the torque of 16 bolts (11-14#, 43-46#, 27-30#, 59-62#) unchanged. Loosen the hexagonal nuts of the remaining 48 bolts in a diagonal cross order, and then re-tighten the hexagonal nuts by hand until they contact the pitch bearing. The numbers of the reserved 16 bolts can be adjusted according to actual conditions to ensure that the bolts are distributed in 4 diagonals, with 4 bolts in each diagonal.

[0044] 3.4 After all the bolts have been tightened to the required torque, confirm that all hexagonal nuts are loosened. Remove the 15# and 47# bolts and insert the locating pins (processed according to the drawing).

[0045] 3.5 Shift the blade pitch so that the locating pin enters the blade bolt hole until the end face of the locating pin hexagonal head is flush with the end face of the bolt. Figure 3 shown.

[0046] 3.6 After the misalignment correction is completed, retighten the 64 connecting bolts in a diagonal cross order. The first tightening number is 4 diagonal bolts (01#, 17#, 33#, 49#). Remove the locating pins in the holes 15# and 47#. (Remove the nuts 1#, 17#, 33#, and 49# in sequence, install the hydraulic nuts, apply rated pressure, and use the 4 diagonal hydraulic nuts to lift the blade as a whole to ensure that the two flange end faces are tightly fitted to prevent sliding and misalignment again.) Figure 4 shown.

[0047] 3.7 After the 64 connecting bolts are installed, apply pre-tightening force according to the requirements of the blade maintenance manual, and gradually increase the pre-tightening force in three steps: first apply 800Nm, then apply 1200Nm, and finally apply 1500Nm (this torque value is a recommended value, the specific applied torque value shall be subject to the host party's documents).

[0048] 3.8 Remove the 4 connecting bolts 01#, 17#, 33# and 49# in sequence, and install one after each one removed. At the same time, install 2 connecting bolts in the 15# and 47# holes.

[0049] 3.9 Apply thread fastener evenly to the threaded end of the new bolt at the threaded assembly part of the non-grooved end, with the amount of glue applied exceeding 1 / 2 of the thread length.

[0050] 3.10 Install the O-ring from the end of the bolt that is not coated with fastener, and the O-ring should be 160-170mm away from the end face of the bolt (the side not coated with fastener).

[0051] 3.11 Use a 16# hexagonal wrench to screw in the new bolt in a clockwise direction on the side coated with fastener. Use a tape measure to measure the length of the bolt extending from the end face of the pitch bearing. The length should be consistent with the length of nearby bolts, with an allowable deviation of ±2mm.

[0052] 3.12 The transition side of the washer is placed toward the hexagonal nut, and the chamfered end of the hexagonal nut is required to face downward.

[0053] 3.13 Special Notes: The thread fastener needs to be cured for 2 hours before applying pre-tightening force.

[0054] Lubricant should be applied evenly to the entire threaded section and the mating surfaces of the nut and washer before reinstalling new bolts. Bolts coated with lubricant must be torque-tightened within 24 hours. Ensure lubricant is applied evenly and to a consistent thickness.

[0055] 3.14 Apply preload force according to the blade maintenance manual, gradually increasing the preload force in three steps: first 800 Nm, then 1200 Nm, and finally 1500 Nm (the torque value is a recommended value, the specific torque value shall be subject to the host's documentation);

[0056] 3.15 Mark the replaced connecting bolts to prevent loosening.

[0057] Note:

[0058] 3.16 The method for confirming the bolt position (hole number) is as follows: looking from the root of the blade to the tip of the blade, the second bolt at the mold seam of the leading edge of the blade is bolt No. 1, and the bolts are No. 2, No. 3, etc. in the clockwise direction.

[0059] 4. Stress analysis of connecting bolts:

[0060] 4.1 When the hexagonal nut is loosened and the blade is pointing vertically downward, the bolt is affected by the weight of the blade. The load borne by a single bolt is calculated as follows:

[0061]

[0062] Among them, m is the blade weight (the blade weight indicated on the nameplate is approximately 11948 kg), g is the acceleration of gravity (9.8 N / m2), N is the number of blade bolts (the number of bolts for a 50.3m blade is 64), and R is the bolt radius (18 mm).

[0063] The calculation shows that:

[0064]

[0065] That is, the load borne by a single bolt is 1.86 MPa, which is much smaller than the yield strength of the bolt, 940 MPa.

[0066] The materials and tools used in the present invention are shown in Table 1.

[0067] Table 1 Materials and tools used in the present invention

[0068]

[0069] The tools required for adjusting the flange surface misalignment of the present invention are shown in Table 2.

[0070] Table 2 Tools required for adjusting flange surface misalignment in the present invention

[0071] Serial number name quantity unit Remark 1 Hydraulic station 1 tower 2 Hollow hydraulic wrench 1 indivual 3 Type 3 wrench head 1 indivual 4 60# sleeve 1 indivual 5 Hydraulic nuts 4 indivual 6 High-pressure hose 5 root With quick connector 7 Allocator 1 indivual 8 manual hydraulic pump 1 tower 9 welding machine 1 tower 10 60# open-end wrench 1 Bundle 11 14# hexagonal wrench 1 root 12 marker 2 branch 13 positioning pins 4 root Φ36

[0072] As described above, the present invention can be preferably implemented.

[0073] All features disclosed in all embodiments in this specification, or steps in all methods or processes implicitly disclosed, except for mutually exclusive features and / or steps, can be combined and / or expanded or replaced in any manner.

[0074] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Based on the technical essence of the present invention and within the spirit and principles of the present invention, any simple modification, equivalent replacement and improvement of the above embodiment shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for adjusting the misalignment of bolt holes in fan blades in mid-air, characterized in that: When replacing the bolts connecting the fan blades and the hub, hydraulic nuts and positioning pins are used as intermediate connectors to achieve mid-air adjustment of the misalignment. The steps include: A, remove M nuts at four locations on the blade; where M ≥ 2; B. Install the hydraulic nut in the corresponding position of the nut removed in step A and apply the rated pressure; C. Remove N bolts from the blade and insert locating pins into the bolt holes corresponding to the N bolts removed; where 1≤N<M; D. Pitch the blades so that the locating pins enter the bolt holes until the hexagonal head of the locating pins is flush with the bolt end faces, thus completing the misalignment correction. E. After the misalignment correction is completed, re-tighten all bolts and remove the positioning pins; F. After all bolts are installed, apply pre-tightening force and gradually increase the pre-tightening force in three steps; G. Remove the hydraulic nuts from the vacancies where the nuts were removed in step A. Install a new bolt for each hydraulic nut removed, and install the bolts inserted into the locating pins at the same time.

2. The method for adjusting the misalignment of bolt holes of fan blades in the air according to claim 1, characterized in that: The method further includes the following steps after step G: H. Apply thread locker evenly to the threaded ends of the new bolts.

3. The method for adjusting the misalignment of bolt holes of fan blades in the air according to claim 2, characterized in that: In step H, the thread fastener is applied to a length exceeding 1 / 2 of the thread length.

4. The method for adjusting the misalignment of bolt holes of fan blades in mid-air according to claim 3, characterized in that: In step H, the thread fastener needs to be cured for 2 hours before applying the pre-tightening force.

5. The method for adjusting the misalignment of bolt holes of fan blades in mid-air according to claim 4, characterized in that: The method further includes the following steps after step H: I. Install the O-ring on the un-adhesive end of the new bolt.

6. The method for adjusting the misalignment of bolt holes in wind turbine blades in mid-air according to claim 5, characterized in that: In step I, the O-ring is 160 mm to 170 mm away from the bolt end face.

7. The method for adjusting the misalignment of bolt holes in wind turbine blades in mid-air according to claim 5, characterized in that: The following steps are also included after step 1: J. Use an Allen wrench to screw in the side of the new bolt that has been coated with fastener in a clockwise direction. Use a tape measure to measure the length of the bolt extending from the end face of the pitch bearing, ensuring that the length of the bolt extending from the adjacent bolt is ±2mm.

8. A method for adjusting the misalignment of bolt holes in wind turbine blades in mid-air according to any one of claims 1 to 7, characterized in that: The following steps are also included before step A: O, adjust the dislocated blades to the vertical blade downward position, manually change the pitch to make the wind wheel rotate freely, and ensure that the blades to be adjusted are in the vertical downward position. After the blades are vertically downward, retract the blades.

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