A method for troubleshooting oil leakage of a main support lower position lock with unknown parameters
By conducting structural investigation, fault reproduction, parts analysis, and repair and assembly of the main strut lower position lock, combined with theoretical calculations and simulation analysis, the oil leakage fault of the main strut lower position lock with unknown parameters was solved, ensuring aircraft safety and economic benefits.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- WUHU STATE-OWNED FACTORY OF MACHINING
- Filing Date
- 2023-12-04
- Publication Date
- 2026-06-02
Smart Images
Figure CN117719693B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of repair technology for main support lower position locks with unknown parameters, specifically a method for troubleshooting oil leakage faults in main support lower position locks with unknown parameters. Background Technology
[0002] The main strut lower locking mechanism is an actuator in the aircraft landing system, used to secure the main landing gear during landing or when the aircraft is parked on the ground. Failure of this mechanism could prevent the aircraft from landing, compromising flight safety. A certain type of main strut lower locking mechanism is a non-domestic product, and its technical parameters are lacking in China. This mechanism has two hydraulic actuators for raising and lowering the main strut, and it has experienced oil leakage during use. Existing troubleshooting and verification methods are all based on detailed product parameters and are not applicable to troubleshooting oil leakage problems in main strut lower locking mechanisms where these parameters are unknown. Summary of the Invention
[0003] To address the aforementioned technical problems, this invention proposes a method for troubleshooting oil leakage faults in the lower main strut lock with unknown parameters. This method is used to reverse-engineer the technical parameters of the lower main strut lock, resolve oil leakage faults, and control the quality and stability of lower main strut lock maintenance, thereby improving aircraft reliability.
[0004] The technical problem to be solved by this invention is achieved by the following technical solution:
[0005] A method for troubleshooting oil leakage in the lower position lock of a main support with unknown parameters includes the following steps:
[0006] Step 1: Conduct a preliminary structural assessment of the lower-level locks on the main support column to determine their operating mechanism.
[0007] This includes conducting preliminary investigations from the outside and structural investigations from the inside, analyzing the components of the hydraulic flow pipeline, and simulating the direction and sequence of hydraulic flow using atmospheric pressure.
[0008] Step 2: Reproduce the product oil leak fault:
[0009] Based on the working mode of the main support lower lock obtained in step 1, the hydraulic actuator of the main support lower lock is pressurized in a gradient manner to make the main support lower lock start to move until the product reproduces the oil leakage fault, and the hydraulic pressure at this time is recorded.
[0010] Step 3, Product Parts Analysis:
[0011] The main support is disassembled down to the smallest unit. The outer surface of each part is treated to expose the part substrate. Metallographic analysis is performed on the parts. Material identification and material coating identification are performed based on the content of each element. The strength of each part is determined based on the identification results.
[0012] Step 4, Analysis of sealing components:
[0013] Qualitative analysis of the material type of the rubber ring was performed, and the rubber compound of the rubber ring in the HB4-56-87 standard was compared to confirm the material code of the rubber ring.
[0014] Step 5: Product repair and assembly:
[0015] First, the damage found during the non-destructive testing of the main support lower lock parts was eliminated through technical means. Second, the coating on the surface of the parts was restored based on the results of material coating identification. The rubber ring of the oil leakage fault area was replaced. Finally, the main support lower lock was reassembled.
[0016] Step 6: Calculate and verify the experimental parameters:
[0017] Step 61: Based on the material strength obtained from the metallographic analysis of the product parts, calculate the theoretical upper limit of the supply pressure that each part can withstand.
[0018] Step 62: Based on the analysis results of the product's part dimensions and materials, establish a three-dimensional model of the product, optimize the mesh generation, conduct simulation analysis on the lower lock of the main support, and obtain the maximum hydraulic pressure P that the part can withstand.
[0019] Step 63: The minimum pressure obtained from theoretical calculations and simulation analysis is the maximum hydraulic pressure P that the part can withstand. Combined with the safety margin X of the product's general design, the test parameter P1 of the product is obtained as P / X.
[0020] Step 64: According to the working method of the product, pressurize the hydraulic actuator of the lower lock of the main support according to the pressure to reproduce the original oil leakage fault, and do not allow the product to have an oil leakage fault.
[0021] Step 65: Pressurize the hydraulic actuator of the lower lock of the main support according to the obtained test parameter P1, and do not allow the product to leak oil.
[0022] Preferably, in step 1, the external inspection is performed by visual inspection and 3D scanner; the internal inspection is performed by industrial CT.
[0023] Preferably, in step 3, based on the applicability of commonly used non-destructive testing methods in the GB / T 5616-2014 standard, magnetic particle testing is selected for ferromagnetic materials, and penetrant testing is selected for other metallic and non-metallic materials.
[0024] Preferably, the specific analysis process in step 4 is as follows: First, check the shape and parting surface of the rubber ring, check the structure of the sealing parts, compare it with the sealing form in the HB4-56-87 standard, and determine its sealing structure form; then measure the dimensions of the parts at the rubber ring installation location, determine the rubber ring number according to the HB4-56-87 standard, and finally obtain the specifications of the rubber ring.
[0025] Preferably, the final specification of the rubber ring is HB4-AA-BB-XXH, where AA is the standard number, BB is the rubber ring material code, XX is the rubber ring number, and H is the movable seal.
[0026] Preferably, the technical means in step 5 include cutting, welding repair, and coating repair.
[0027] Preferably, the formula for calculating the theoretical upper limit of the supply pressure that each component can withstand in step 61 is as follows:
[0028] The axial stress borne by the hydraulic actuator cylinder is: σ1=PD(2-μ) / 4s≤σ, which gives P≤4sσ / D(2-μ);
[0029] The circumferential stress borne by the hydraulic actuator cylinder is: σ2=PD / 2s≤σ, which leads to P≤2sσ / D;
[0030] Where s is the thickness of the part; D is the inner diameter of the part; σ is the material strength of the part; and μ is Poisson's ratio.
[0031] The beneficial effects of this invention are:
[0032] Compared with existing technologies, this invention provides a method for troubleshooting oil leakage faults in the lower position lock of a main support with unknown parameters. This method can effectively eliminate oil leakage faults in a certain type of lower position lock with unknown parameters. It is scientific, reasonable, simple, and effective, and can be used to troubleshoot similar products with unknown parameters, solving similar technical problems. It can control the quality and stability of the repair of lower position locks with unknown parameters, overcome the economic losses caused by the inability to repair the product, and can be applied to the repair process of lower position locks with main support. It has good application prospects and significant economic benefits. Attached Figure Description
[0033] The present invention will be further described below with reference to the accompanying drawings and embodiments:
[0034] Figure 1 This is a flowchart of the present invention;
[0035] Figure 2 This is a schematic diagram simulating air pressure flow.
[0036] Figure 3 This is a schematic diagram for simulation analysis. Detailed Implementation
[0037] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with the accompanying drawings and embodiments.
[0038] like Figure 1 As shown, a method for troubleshooting oil leakage in a main support lower lock with unknown parameters is presented. First, the original structure of the main support lower lock is investigated to determine its specific operating mode. Then, gradient pressure is applied to the hydraulic actuator of the main support lower lock to reproduce the oil leakage fault. After fault reproduction, the product parts are analyzed to determine their material properties. Next, the sealing parts of the main support lower lock are analyzed to confirm the specific specifications of the sealing structure and sealing rings. After confirmation, the faulty parts of the product are repaired, and then reassembled. Finally, the experimental parameters of the product are calculated using both theoretical calculations and finite element analysis, and the oil leakage fault in the main support lower lock is verified through experiments to ensure that it has been eliminated.
[0039] The specific steps are as follows:
[0040] Step 1: Conduct a preliminary structural survey of the lower lock of the main support column.
[0041] First, the external components of the main support lower lock are inspected visually and using a 3D scanner to determine the mechanical movement direction and stroke of the external parts, providing a preliminary understanding of the main support lower lock structure. Then, industrial CT scans are used to clarify the internal component composition and working limits. Finally, the main support lower lock is decomposed into its smallest unit to clarify the detailed structural composition. After decomposition, components involving hydraulic flow lines are analyzed, and the direction and sequence of hydraulic flow are simulated using atmospheric pressure to determine the working mode of the main support lower lock, followed by 3D modeling. Figure 2 As shown.
[0042] Step 2: Reproduce the product oil leak fault
[0043] According to the working mode of the main support lower position lock, the hydraulic actuator of the main support lower position lock is pressurized in a gradient manner to make the main support lower position lock start to move until the product reproduces the oil leakage fault, and the hydraulic pressure at this time is recorded. As shown in Table 1 below.
[0044] Table 1. Pressure gauge for fault reproduction
[0045]
[0046] Step 3: Product Parts Analysis
[0047] First, based on the product structure design, tooling, or general tools, the main support lower lock is disassembled to the component level. Then, metallographic analysis is performed on the outer surface of each component, and the results are shown in Table 2. The surface coating of the material is identified based on the content of each element in the analysis results. Next, plastic particles are blown onto each component to expose the component substrate, and metallographic analysis is performed on the component substrate. The substrate material of the component is identified based on the content of each element in the analysis results. Finally, the strength of each component is determined based on the identification results of the component substrate material. In accordance with the applicability of commonly used non-destructive testing methods in GB / T 5616-2014 standard, magnetic particle testing (MT) is selected for ferromagnetic materials, and penetrant testing (PT) is selected for other metallic and non-metallic materials.
[0048] Table 2 Metallographic Analysis Results of Parts
[0049]
[0050] Report conclusion: Chromium plating on the material surface; Recommended grade: 30CrMnSiNi2A
[0051] Step 4: Analysis of Sealing Parts
[0052] The material type of the rubber ring was qualitatively analyzed and compared with the rubber compound in the HB4-56-87 standard to confirm the material code of the rubber ring. The results of the rubber ring material analysis are shown in Table 3.
[0053] The specific process for confirming the rubber ring material code is as follows: First, check the shape and parting surface of the rubber ring, examine the structure of the sealing parts, and compare it with the sealing type in the HB4-56-87 standard to determine its sealing structure type; then measure the dimensions of the parts at the rubber ring installation location, determine the rubber ring number according to the HB4-56-87 standard, and finally obtain the rubber ring specification: HB4-AA-BB-XXH. Where, AA: standard number; BB: rubber ring material code; XX: rubber ring number; H: active seal.
[0054] Table 3. Rubber Ring Material Analysis Results
[0055]
[0056] The report concludes that the rubber ring is classified as nitrile rubber.
[0057] Step 5: Product Repair and Assembly
[0058] During repair, the damage found during the non-destructive testing of the main support lower lock parts is first eliminated through cutting, welding, and coating repair techniques. Then, the coating on the surface of the parts is restored based on the identification results of the material surface coating. The rubber ring of the oil leakage fault area is replaced. Finally, the main support lower lock is reassembled.
[0059] Step 6: Calculate and verify the experimental parameters.
[0060] Based on the material strength obtained from the metallographic analysis of the product parts, calculate the theoretical upper limit of the supply pressure that each part can withstand.
[0061] The axial stress borne by the hydraulic actuator cylinder is: σ1=PD(2-μ) / 4s≤σ, which gives P≤4sσ / D(2-μ);
[0062] The circumferential stress borne by the hydraulic actuator cylinder is: σ2=PD / 2s≤σ, which leads to P≤2sσ / D;
[0063] Where s is the thickness of the part (mm); D is the inner diameter of the part (mm); σ is the material strength of the part (MPa); and μ is Poisson's ratio.
[0064] The theoretical upper limit of the supply pressure that each component can withstand is shown in Table 4.
[0065] Table 4 Summary of Pressure Limits for Various Components
[0066] Serial number Material strength Poisson's ratio Inner diameter Thickness Upper pressure limit 1 885 0.30 26 2.5 170 2 885 0.30 15 2 236 3 980 0.27 22 2.5 223 … … … … … …
[0067] Based on the analysis results of the product's component dimensions and materials, a 3D model of the product is established, the mesh generation is optimized, and simulation analysis is performed on the lower lock of the main support column. Figure 3 As shown, the maximum hydraulic pressure P that the component can withstand is obtained.
[0068] The minimum pressure value derived from theoretical calculations and simulation analysis is the maximum hydraulic pressure P that the component can withstand. Combined with the safety margin X of the product's general design, the test parameter P1 = P / X is derived. Based on the product's operating mode, the hydraulic actuator of the lower main support lock is pressurized to reproduce the original oil leakage fault; oil leakage is not permitted. The hydraulic actuator of the lower main support lock is pressurized according to the derived test parameter P1; oil leakage is not permitted.
[0069] 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 troubleshooting oil leakage faults in the lower position lock of a main support column with unknown parameters, characterized in that: Includes the following steps: Step 1: Conduct a preliminary structural assessment of the lower-level locks on the main support column to determine their operating mechanism. This includes conducting preliminary investigations from the outside and structural investigations from the inside, analyzing the components of the hydraulic flow pipeline, and simulating the direction and sequence of hydraulic flow using atmospheric pressure. Step 2: Reproduce the product oil leak fault: Based on the working mode of the main support lower lock obtained in step 1, the hydraulic actuator of the main support lower lock is pressurized in a gradient manner to make the main support lower lock start to move until the product reproduces the oil leakage fault, and the hydraulic pressure at this time is recorded. Step 3, Product Parts Analysis: The main support is disassembled down to the smallest unit. The outer surface of each part is treated to expose the part substrate. Metallographic analysis is performed on the parts. Material identification and material coating identification are performed based on the content of each element. The strength of each part is determined based on the identification results. Step 4, Analysis of sealing components: Qualitative analysis of the material type of the rubber ring was performed, and the rubber compound of the rubber ring in the HB4-56-87 standard was compared to confirm the material code of the rubber ring. Step 5: Product repair and assembly: First, the damage found during the non-destructive testing of the main support lower lock parts was eliminated through technical means. Second, the coating on the surface of the parts was restored based on the results of material coating identification. The rubber ring of the oil leakage fault area was replaced. Finally, the main support lower lock was reassembled. Step 6: Calculate and verify the experimental parameters: Step 61: Based on the material strength obtained from the metallographic analysis of the product parts, calculate the theoretical upper limit of the supply pressure that each part can withstand. Step 62: Based on the analysis results of the product's part dimensions and materials, establish a three-dimensional model of the product, optimize the mesh generation, conduct simulation analysis on the lower lock of the main support, and obtain the maximum hydraulic pressure P that the part can withstand. Step 63: The minimum pressure obtained from theoretical calculations and simulation analysis is the maximum hydraulic pressure P that the part can withstand. Combined with the safety margin X of the product's general design, the test parameter P1 = P / X of the product is obtained. Step 64: According to the working method of the product, pressurize the hydraulic actuator of the lower lock of the main support according to the pressure to reproduce the original oil leakage fault, and do not allow the product to have an oil leakage fault. Step 65: Pressurize the hydraulic actuator of the lower lock of the main support according to the obtained test parameter P1, and do not allow the product to leak oil.
2. The method for troubleshooting oil leakage faults in the lower position lock of a main support with unknown parameters according to claim 1, characterized in that: In step 1, external inspection is performed using visual inspection and 3D scanners; internal inspection is performed using industrial CT.
3. The method for troubleshooting oil leakage faults in the lower position lock of a main support with unknown parameters according to claim 1, characterized in that: In step 3, based on the applicability of commonly used non-destructive testing methods in the GB / T 5616-2014 standard, magnetic particle testing is selected for ferromagnetic materials, and penetrant testing is selected for other metallic and non-metallic materials.
4. The method for troubleshooting oil leakage faults in the lower position lock of a main support with unknown parameters according to claim 1, characterized in that: The specific process in step 4 is as follows: First, check the shape and parting surface of the rubber ring, check the structure of the sealing parts, compare it with the sealing form in the HB4-56-87 standard, and determine its sealing structure form; then measure the dimensions of the parts at the rubber ring installation location, determine the rubber ring number according to the HB4-56-87 standard, and finally obtain the specifications of the rubber ring.
5. The method for troubleshooting oil leakage faults in the lower position lock of a main support with unknown parameters according to claim 4, characterized in that: The final specification of the rubber ring is HB4-AA-BB-XXH, where AA is the standard number, BB is the material code of the rubber ring, XX is the rubber ring number, and H is the movable seal.
6. The method for troubleshooting oil leakage faults in the lower position lock of a main support with unknown parameters according to claim 1, characterized in that: The technical means in step 5 include machining, welding repair, and coating repair.
7. The method for troubleshooting oil leakage faults in the lower position lock of a main support with unknown parameters according to claim 1, characterized in that: The formula for calculating the theoretical upper limit of the supply pressure that each component can withstand in step 61 is as follows: The axial stress borne by the hydraulic actuator cylinder is: σ1=PD(2-μ) / 4s≤σ, which gives P≤4sσ / D(2-μ); The circumferential stress borne by the hydraulic actuator cylinder is: σ2=PD / 2s≤σ, which leads to P≤2sσ / D; Where s is the thickness of the part; D is the inner diameter of the part; σ is the material strength of the part; and μ is Poisson's ratio.