A method for tightening the lug bolts of a main landing gear retracted position locking spring device

Abstract

This invention relates to the field of main landing gear retractable position lock repair technology, specifically a method for tightening the lug bolts of the main landing gear retractable position lock spring device. The specific steps are as follows: S1, theoretical force analysis; S2, actual torque; S3, loosening mechanism study; S4, lug bolt repair; S5, experimental verification; S6, determination of tightening method. Theoretical force analysis is performed on the lug bolts of the main landing gear retractable position lock spring device. Simultaneously, the torque range provided by the compression deformation of the thin metal edge is measured during the disassembly of the lug bolt, and the data is statistically analyzed. Next, the loosening mechanism of the lug bolt is studied. The torque range provided by different tightening methods is analyzed using finite element analysis, and the influence of different tightening methods on the material strength of the spring device is analyzed. Through experimental verification, an effective tightening method for the lug bolts of the spring device is determined, improving the main landing gear retractable position lock repair standard and enhancing the product's repair reliability.

Description

Technical Field

[0001] This invention relates to the field of main landing gear retractable position lock repair technology, specifically a method for tightening the lug bolts of the main landing gear retractable position lock spring device. Background Technology

[0002] The main landing gear retraction position lock is an actuator component of the landing system, primarily composed of a transmission mechanism (including a lock body and actuator cylinder), a spring device, and a termination switch mechanism. Its function is to lock the main landing gear when it retracts during flight or on the ground, and to transmit the electrical signal for retracting the main landing gear door. If the spring device's lug bolts fail to tighten properly, they may loosen, damaging the bolts and causing the main landing gear retraction position lock's electrical signal transmission to fail, affecting flight safety. During main landing gear retraction position lock repair, the spring device's lug bolts must be tightened to ensure reliable connection. If they fail, the main landing gear retraction position lock must be repaired. Currently, unrepaired spring devices tighten the lug bolts through metal thin-edge compression deformation. Repairing this requires damaging the deformed metal thin-edge and disassembling the lug bolts for non-destructive testing, resulting in a lack of effective tightening methods when assembling the repaired spring device's lug bolts. Summary of the Invention

[0003] To address the aforementioned problems, this invention proposes a method for tightening the lug bolts of the main landing gear retractable position locking spring device.

[0004] A method for tightening the lug bolts of the main landing gear retracted position lock spring device, the specific steps of which are as follows:

[0005] S1. Theoretical force analysis:

[0006] 101. The forces acting on the spring mechanism during the movement of the four-bar linkage of the main landing gear retraction position lock are analyzed through theoretical calculations. The specific calculation process is as follows:

[0007] Theoretical calculations for spring devices:

[0008] Spring outer diameter: D = D0 + d;

[0009] Wrap ratio:

[0010] Stress correction factor:

[0011] Theoretical force value of the spring device:

[0012] Actual force value of the spring device: F 实 =KF 理 ;

[0013] f: Deformation of the spring mechanism;

[0014] G: Shear modulus: 74480MPa;

[0015] D0: Mean diameter of the spring;

[0016] d: Diameter of spring steel wire;

[0017] n: Number of valid laps;

[0018] 102. Analyze the forces acting on the earring bolts and, in conjunction with the preload of the threaded connection, determine the range of torques provided by the compressive deformation of the thin metal edge. The specific steps are as follows:

[0019] The force on the earring bolt is the force generated by the deformation of the spring mechanism.

[0020] F1: Initial force value of the spring device;

[0021] ΔL: The extension amount of the spring device at different positions during the movement of the four-bar linkage;

[0022] Force value during movement:

[0023] Force on the earring bolt: F = F1 + F f ;

[0024] The preload torque for the threaded connection is M = 0.001K. k P0d;

[0025] K k Tightening torque coefficient;

[0026] d: Nominal diameter of the thread;

[0027] P0: Select the appropriate preload force according to the nominal diameter of the earring bolt;

[0028] Based on the calculated force F on the earring bolt, the theoretical required torque M1 = 0.001K is calculated. k Fd; then the torque range required for the compression deformation of the thin metal edge is M2 = M1 - M;

[0029] S2, Actual Torque:

[0030] 201. Decomposition Torque Statistics: This involves statistically analyzing the torque provided by the compressive deformation of the thin metal edge during decomposition and calculating the variance of the actual measurement data. x) 2 Select an appropriate level of data dispersion;

[0031] 202. Data statistical analysis: Based on theoretical force analysis, the required torque range for further optimization is 1.5M2;

[0032] S3. Study on the mechanism of relaxation:

[0033] 301. By analyzing the product structure of the lug bolts of the main landing gear retractable position lock spring device, finite element analysis was performed on different fastening methods;

[0034] 302. The least squares method was used to perform numerical simulation on the simulation results to obtain the torque range corresponding to different fastening methods, and the influence of different fastening methods on the material strength was analyzed.

[0035] S4. Earring bolt repair:

[0036] 401. Based on the results of theoretical force analysis, actual torque statistical analysis and finite element simulation analysis, repair the fastening parts of the lug bolts of the main landing gear retractable position lock spring device, and then fasten them according to different fastening methods.

[0037] 402. Drill holes at different positions on the spring device lug bolts;

[0038] 403. Select different adhesives and apply them evenly around the circumference of the threaded rod of the spring device ear bolt. Verify different application sizes based on the length of the threaded rod of the ear bolt, with each size spaced 1.0 mm apart.

[0039] S5. Experimental verification:

[0040] 501. After repairing the spring device lug bolts, assemble the product and test it according to the actual working conditions of the main landing gear retracted position lock.

[0041] 502. After the test, disassemble the spring device ear bolts and perform non-destructive testing on the ear bolts to verify the impact of different fastening methods on product quality.

[0042] S6. Tightening Method Determination: Based on the results of theoretical analysis and experimental verification, and combined with the pass rate of non-destructive testing of the lug bolts after experimental disassembly, determine the tightening method of the lug bolts of the main landing gear retraction position lock spring device, improve product maintenance standards, and enhance the repair reliability of the product.

[0043] The product in step S102 is an unlubricated oxide surface, and 0.24 is selected.

[0044] The wrench in step S201 is a digital wrench with torque display function.

[0045] The compression deformation of the thin metal edge in step S202 requires a torque of M2. Since this product is a landing system actuator, a safety margin of 1.5 times is selected.

[0046] The finite element analysis in step S301 specifically involves establishing a product simulation model, setting material properties, setting boundary conditions for loads, and optimizing mesh generation to obtain simulation results of the fastening torque corresponding to different fastening methods.

[0047] In step S402, the initial position is the head of the earring bolt. To avoid affecting the movement of the spring device, the drilling positions differ by 1.0mm. The drilling sizes of the earring bolts at the same drilling positions are Φ0.6mm, Φ0.8mm, Φ1.0mm, and Φ1.2mm, respectively. Different specifications of cotter pins are selected for verification based on the hole diameter.

[0048] In step S502, the test consists of 2000 opening and closing tests, and the tightness of the earring bolts is checked during the test.

[0049] In step S6, the required torque M2 is calculated theoretically. After the product undergoes 2000 tests, the torque is checked during the disassembly process to confirm whether the torque meets the 1.5 times safety margin.

[0050] The beneficial effects of this invention are as follows: First, a theoretical force analysis is performed on the lug bolts of the main landing gear retractable position lock spring device. Simultaneously, the range of torque provided by the compression deformation of the thin metal edge is measured during the disassembly of the lug bolts, and the data is statistically analyzed. Second, the loosening mechanism of the lug bolts is studied. The torque range provided by different tightening methods is analyzed using finite element analysis, and the influence of different tightening methods on the material strength of the spring device is also analyzed. Finally, the effective tightening method for the lug bolts of the spring device is determined through experimental verification, thus improving the maintenance standards for the main landing gear retractable position lock and enhancing the repair reliability of the product. Attached Figure Description

[0051] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0052] Figure 1 This is a cross-sectional schematic diagram of the spring device earring bolt of the present invention;

[0053] Figure 2 This is a schematic front view of the spring device earring bolt of the present invention;

[0054] Figure 3 This is a schematic diagram of the process of the present invention;

[0055] Figure 4 This is a schematic diagram of the movement of the spring device of the present invention;

[0056] Figure 5 This is a schematic diagram of the loosening mechanism research process in step S3 of the present invention;

[0057] Figure 6This is a schematic diagram of the experimental verification process for step S5 of the present invention. Detailed Implementation

[0058] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below.

[0059] like Figures 1 to 6 As shown, a method for tightening the lug bolts of the main landing gear retracted position lock spring device is characterized by the following specific steps:

[0060] S1. Theoretical force analysis:

[0061] 103. The forces acting on the spring mechanism during the movement of the four-bar linkage of the main landing gear retraction position lock are analyzed through theoretical calculations. The specific calculation process is as follows:

[0062] Theoretical calculations for spring devices:

[0063] Spring outer diameter: D = D0 + d;

[0064] Wrap ratio:

[0065] Stress correction factor:

[0066] Theoretical force value of the spring device:

[0067] Actual force value of the spring device: F 实 =KF 理 ;

[0068] f: Deformation of the spring device, in mm;

[0069] G: Shear modulus: 74480MPa;

[0070] D0: Mean diameter of the spring, in mm;

[0071] d: Diameter of spring steel wire, in mm;

[0072] n: Number of valid laps;

[0073] 104. Analyze the forces acting on the earring bolts and, in conjunction with the preload of the threaded connection, determine the range of torques provided by the compressive deformation of the thin metal edge. The specific steps are as follows:

[0074] The force on the earring bolt is the force generated by the deformation of the spring mechanism.

[0075] F1: Initial force value of the spring device;

[0076] ΔL: The extension amount of the spring device at different positions during the movement of the four-bar linkage, in mm;

[0077] Force value during movement:

[0078] Force on the earring bolt: F = F1 + F f ;

[0079] The preload torque for the threaded connection is M = 0.001K. k P0d;

[0080] K k Tightening torque coefficient;

[0081] d: Nominal thread diameter, in mm;

[0082] P0: Select the appropriate preload force based on the nominal diameter of the earring bolt, in N;

[0083] Based on the calculated force F on the earring bolt, the theoretical required torque M1 = 0.001K is calculated. k Fd; then the torque range required for the compression deformation of the thin metal edge is M2 = M1 - M;

[0084] S2, Actual torque:

[0085] 203. Statistical Analysis of Decomposition Torque: This involves statistically analyzing the torque provided by the compressive deformation of the thin metal edge during decomposition and calculating the variance of the actual measurement data. With an appropriate degree of data dispersion selected, the moment statistical analysis table is shown below;

[0086] Serial Number Part Number Decomposition of torque Dispersion Torque range 1 ** ** ** ** 2 ** ** ** ** 3 ** ** ** ** … … … … …

[0087] 204. Data Statistical Analysis: Based on theoretical force analysis, the required torque range for further optimization is 1.5M2;

[0088] S3. Study on the mechanism of relaxation:

[0089] 303. By analyzing the product structure of the lug bolts of the main landing gear retractable position locking spring device, finite element analysis was performed on different fastening methods;

[0090] 304. The least squares method was used to perform numerical simulation on the simulation results to obtain the torque range corresponding to different fastening methods, and the influence of different fastening methods on the material strength was analyzed.

[0091] S4. Earring bolt repair:

[0092] 401. Based on the results of theoretical force analysis, actual torque statistical analysis and finite element simulation analysis, repair the fastening parts of the lug bolts of the main landing gear retractable position lock spring device, and then fasten them according to different fastening methods.

[0093] 402. Drill holes at different positions on the spring device lug bolts;

[0094] 403. Select different adhesives and apply them evenly along the circumference of the threaded rod of the spring device ear bolt. Select different adhesive application sizes according to the length of the threaded rod of the ear bolt for verification. The size interval is 1.0mm. The adhesive application table of the ear bolt is shown below.

[0095] Serial Number Rubber Adhesive application dimensions (distance from bolt head) 1 ** ** 2 ** ** 3 ** ** … … …

[0096] S5. Experimental verification:

[0097] 501. After repairing the spring device lug bolts, assemble the product and test it according to the actual working conditions of the main landing gear retracted position lock.

[0098] 502. After the test, disassemble the spring device ear bolts and perform non-destructive testing on the ear bolts to verify the impact of different fastening methods on product quality.

[0099] S6. Tightening Method Determination: Based on the results of theoretical analysis and experimental verification, and combined with the pass rate of non-destructive testing of the lug bolts after experimental disassembly, the tightening method of the lug bolts of the main landing gear retraction position lock spring device was determined. This improved the product maintenance standards and enhanced the product's repair reliability. The statistical table of results for different tightening methods is shown below:

[0100]

[0101] Repair the lug bolt fastening points of the main landing gear retraction position lock spring device to form the required fastening method, and conduct tests according to the actual use conditions of the product. During the test, check the tightness of the spring device lug bolt. After the test, disassemble the spring device lug bolt and perform non-destructive testing to verify the impact of different fastening methods on product quality.

[0102] The product in step S102 is an unlubricated oxide surface, and 0.24 is selected.

[0103] The wrench in step S201 is a digital wrench with torque display function.

[0104] The compression deformation of the thin metal edge in step S202 requires a torque of M2. Since this product is a landing system actuator, a safety margin of 1.5 times is selected.

[0105] like Figure 1 , Figure 2 , Figure 4As shown in the figure, reference numeral a represents the earring bolt, reference numeral b represents the spring device, and reference numeral c represents the location where the thin metal edge deforms and is fastened.

[0106] The finite element analysis in step S301 specifically involves establishing a product simulation model, setting material properties, setting boundary conditions for loads, and optimizing mesh generation to obtain simulation results of the fastening torque corresponding to different fastening methods.

[0107] The finite element analysis in step S301 is performed using general simulation software, such as Abaqus.

[0108] Based on finite element analysis, an analysis of the fastening methods for earring bolts was conducted. A product simulation model was established, and finite element analysis was carried out in combination with different fastening methods to obtain the simulation results of the fastening torque corresponding to different fastening methods. Numerical simulation was performed on the simulation results to obtain the torque range corresponding to different fastening methods and their impact on material strength.

[0109] The least squares method used in step S302 for numerical simulation is a general method, and the general formula is y = a + bx.

[0110] Based on the theoretical force analysis of the lug bolts of the main landing gear retraction position lock spring device, the torque range was determined, and experimental verification was carried out to obtain an effective fastening method for the product, improve the product maintenance standards, and enhance the product's repair reliability.

[0111] In step S402, the initial position is the head of the earring bolt. To avoid affecting the movement of the spring device, the drilling positions differ by 1.0mm. The drilling sizes of the earring bolts at the same drilling positions are Φ0.6mm, Φ0.8mm, Φ1.0mm, and Φ1.2mm, respectively. Different specifications of cotter pins are selected for verification based on the hole diameter.

[0112] In step S502, the test consists of 2000 cycles of opening and closing, and the tightness of the earring bolts is checked during the test. The drilling diagram of the earring bolts is shown below:

[0113] Serial Number Length from the head of the earring bolt aperture Cotter pin specifications 1 ** ** ** 2 ** ** ** 3 ** ** ** … … … …

[0114] In step S6, the required torque M2 is calculated theoretically. After the product undergoes 2000 tests, the torque is checked during the disassembly process to confirm whether the torque meets the 1.5 times safety margin.

[0115] Based on measured data, we conducted an analysis of the lug bolt tightening method, selected an appropriate level of data dispersion, and analyzed the torque range provided by the original tightening method of the lug bolt of the main landing gear retraction position lock spring device.

[0116] Theoretical stress analysis was performed on the lug bolts of the main landing gear retractable position lock spring device. Simultaneously, the torque range provided by the compression deformation of the thin metal edge during the disassembly of the lug bolts was measured and statistically analyzed. Secondly, the loosening mechanism of the lug bolts was studied. Finite element analysis was used to analyze the torque range provided by different tightening methods, and the influence of different tightening methods on the material strength of the spring device was also analyzed. Finally, the effective tightening method for the lug bolts of the spring device was determined through experimental verification, thus improving the maintenance standards for the main landing gear retractable position lock and enhancing the repair reliability of the product.

[0117] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely prisms of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for tightening the lug bolts of a main landing gear retracted position locking spring device, characterized in that: The specific steps are as follows: S1. Theoretical force analysis:

101. The forces acting on the spring mechanism during the movement of the four-bar linkage of the main landing gear retraction position lock are analyzed through theoretical calculations. The specific calculation process is as follows: Theoretical calculation of spring device: Spring outer diameter: D = D0 + d; Wrap ratio: Stress correction factor: Theoretical force value of the spring device: Actual force value of the spring device: F 实 =KF 理 ; f: Deformation of the spring mechanism; G: Shear modulus: 74480MPa; D0: Mean diameter of the spring; d: Diameter of spring steel wire; n: Number of valid laps; 102. Analyze the forces acting on the earring bolts and, in conjunction with the preload of the threaded connection, determine the range of torques provided by the compressive deformation of the thin metal edge. The specific steps are as follows: The force on the earring bolt is the force generated by the deformation of the spring mechanism. F1: Initial force value of the spring device; ΔL: The extension amount of the spring device at different positions during the movement of the four-bar linkage; Force value during movement: Force on the earring bolt: F = F1 + F f ; The preload torque for the threaded connection is M = 0.001K. k P0d; K k Tightening torque coefficient; d: Nominal diameter of the thread; P0: Select the appropriate preload force according to the nominal diameter of the earring bolt; Based on the calculated force F on the earring bolt, the theoretical required torque M1 = 0.001K is calculated. k Fd; then the torque range required for the compression deformation of the thin metal edge is M2 = M1 - M; S2, Actual torque:

201. Decomposition Torque Statistics: This involves statistically analyzing the torque provided by the compressive deformation of the thin metal edge during decomposition and calculating the variance of the actual measurement data. Select an appropriate level of data dispersion; 202. Data statistical analysis: Based on theoretical force analysis, the required torque range for further optimization is 1.5M2; S3. Study on the mechanism of relaxation:

301. By analyzing the product structure of the lug bolts of the main landing gear retractable position lock spring device, finite element analysis was performed on different fastening methods; 302. The least squares method was used to perform numerical simulation on the simulation results to obtain the torque range corresponding to different fastening methods, and the influence of different fastening methods on material strength was analyzed. S4. Earring bolt repair:

401. Based on the results of theoretical force analysis, actual torque statistical analysis and finite element simulation analysis, repair the fastening parts of the lug bolts of the main landing gear retractable position lock spring device, and then fasten them according to different fastening methods.

402. Drill holes at different positions on the spring device lug bolts; 403. Select different adhesives and apply them evenly around the circumference of the threaded rod of the spring device ear bolt. Verify different application sizes based on the length of the threaded rod of the ear bolt, with each size spaced 1.0 mm apart. S5. Experimental verification:

501. After repairing the spring device lug bolts, assemble the product and test it according to the actual working conditions of the main landing gear retracted position lock.

502. After the test, disassemble the spring device ear bolts and perform non-destructive testing on the ear bolts to verify the impact of different fastening methods on product quality. S6. Tightening Method Determination: Based on the results of theoretical analysis and experimental verification, and combined with the pass rate of non-destructive testing of the lug bolts after experimental disassembly, determine the tightening method of the lug bolts of the main landing gear retraction position lock spring device, improve product maintenance standards, and enhance the repair reliability of the product.

2. The method for fastening the lug bolts of the main landing gear retracted position lock spring device according to claim 1, characterized in that: The product in step S102 is an unlubricated oxide surface, and 0.24 is selected.

3. The method for fastening the lug bolts of the main landing gear retracted position lock spring device according to claim 1, characterized in that: The wrench in step S201 is a digital wrench with torque display function.

4. The method for fastening the lug bolts of the main landing gear retracted position lock spring device according to claim 1, characterized in that: The compression deformation of the thin metal edge in step S202 requires a torque of M2. Since this product is a landing system actuator, a safety margin of 1.5 times is selected.

5. The method for fastening the lug bolts of the main landing gear retracted position locking spring device according to claim 1, characterized in that: The finite element analysis in step S301 specifically involves establishing a product simulation model, setting material properties, setting boundary conditions for loads, and optimizing mesh generation to obtain simulation results of the fastening torque corresponding to different fastening methods.

6. The method for fastening the lug bolts of the main landing gear retracted position lock spring device according to claim 1, characterized in that: In step S402, the initial position is the head of the earring bolt. To avoid affecting the movement of the spring device, the drilling positions differ by 1.0mm. The drilling sizes of the earring bolts at the same drilling positions are Φ0.6mm, Φ0.8mm, Φ1.0mm, and Φ1.2mm, respectively. Different specifications of cotter pins are selected for verification based on the hole diameter.

7. The method for fastening the lug bolts of the main landing gear retracted position lock spring device according to claim 1, characterized in that: In step S502, the test consists of 2000 opening and closing tests, and the tightness of the earring bolts is checked during the test.

8. The method for tightening the lug bolts of the main landing gear retracted position lock spring device according to claim 1, characterized in that: In step S6, the required torque M2 is calculated theoretically. After the product undergoes 2000 tests, the torque is checked during the disassembly process to confirm whether the torque meets the 1.5 times safety margin.

Images