A method for reducing the working vibration of a helicopter transmission gear

Abstract

The present application belongs to the technical field of mechanical structure, and particularly relates to a method for reducing working vibration of a gear of a helicopter transmission system. The method uses a three-dimensional model of the gear or the gear ring and finite element calculation to obtain the first four modal frequencies. According to the gear structure, slots are formed at the gear web, the inner and outer diameters of the gear ring, or the gear weight-reducing holes before static or dynamic balancing of the gear. A damping ring or a damping block is installed at the slots, and then modal testing is performed. By adjusting the damping ring or the damping block, the working vibration is relatively reduced, and the processability and maintainability of the large gear are improved. The method can reduce harmful working vibration of the gear or the gear ring without changing the original structure, does not additionally increase the weight of the gear or the gear ring, and has repeatability. The method can be repeatedly improved according to the modal test results of each adjustment to achieve the best effect of reducing harmful working vibration.

Description

Technical Field

[0001] This invention belongs to the field of mechanical structure technology, and specifically relates to a method for reducing the working vibration of gears in a helicopter transmission system. Background Technology

[0002] Gears or gear rings used in helicopter transmission systems are characterized by high strength, light weight, low vibration requirements, and high safety. Currently, gears or gear rings used in helicopter transmission systems are all made of steel, mostly machined from a single forging or bar stock, or from multiple sections of metal welded together before machining. To ensure operational safety, a large safety factor is often used; for gears operating at higher speeds, static or dynamic balancing is typically performed to ensure smooth operation.

[0003] While static or dynamic balancing of gears or gear rings can ensure the gears' own operational balance, the operating vibrations generated by the gears or gear rings in the transmission system or the entire aircraft can easily be the same as or similar to the vibration frequencies of other components in the transmission system or the entire aircraft, causing resonance. Furthermore, dynamic balancing of large gear ring-type parts is quite difficult. Summary of the Invention

[0004] The purpose of this invention is to propose a method for reducing the working vibration of gears in a helicopter transmission system, which solves the problem that the working vibration generated by the operation of gears or gear rings is easily the same as or similar to the vibration frequency of other components in the transmission system or the whole machine, causing resonance.

[0005] Technical solution of the present invention

[0006] A method for reducing the operating vibration of gears in a helicopter transmission system involves using a three-dimensional model of the gear or gear ring and finite element method to calculate the first four modal frequencies of the gear or gear ring. Based on the gear structure, slots are cut into the gear or gear ring during static or dynamic balancing. Vibration damping rings or blocks are installed at the slots, followed by modal testing. The operating vibration is relatively reduced by adjusting the vibration damping rings or blocks.

[0007] Furthermore, the specific steps of the method are as follows:

[0008] Step 1: Determine the vibration frequencies of the helicopter's transmission system and the entire aircraft;

[0009] Step 2: Using the 3D model and finite element method, calculate the first four modal frequencies of the gear or gear ring, and determine whether the calculation results are the same as or similar to the vibration frequencies of the helicopter transmission system and the whole aircraft.

[0010] Step 3: Select the slotting position based on the frequency determination result and the gear ring structure;

[0011] Step 4: Design vibration damping rings or blocks according to the gear or gear ring structure;

[0012] Step 5: Select the material for the damping ring or damping block;

[0013] Step 6: After installing damping rings or damping blocks at the slotted positions of the gear or gear ring 3D model, perform modal analysis again;

[0014] Step 7: If the modal analysis frequency does not meet the requirements, repeat steps 3 to 6. If the modal analysis frequency meets the requirements, proceed to step 8.

[0015] Step 8: After the modal analysis frequency meets the requirements, perform trial production of gears or gear rings and damping rings or damping blocks;

[0016] Step 9: Install the damping ring or damping block onto the gear or gear ring, and perform modal testing on the gear or gear ring after assembling the damping ring or damping block to verify the reduction of working vibration.

[0017] Step 10: Perform static or dynamic balancing on the gear or gear ring. During the static or dynamic balancing process, adjust the weight of the damping ring or damping block to reduce the working vibration of the gear or gear ring.

[0018] Furthermore, in step two, the gear or gear ring is modeled using CATIA / UG modeling software. This step is to allow for local adjustments to the 3D model of the gear or gear ring before performing finite element analysis if the modal analysis frequency does not meet the requirements and the slotting position needs to be selected repeatedly in step seven, thus avoiding repeated modeling and repetitive work.

[0019] Furthermore, in step three, before static or dynamic balancing of the gear, grooves are made on the gear spokes, the inner and outer diameters of the gear ring, or the weight-reducing holes of the gear, according to the gear structure. This step is to allow for weight removal on the damping ring or damping block during static or dynamic balancing of the gear or gear ring, thereby achieving static or dynamic balance and avoiding the need for reprocessing the gear or gear ring base during balancing, reducing the risk of abnormal gear or gear ring processing.

[0020] Furthermore, in step five, a material identical or similar to that of the gear or gear ring is selected as the machining material for the damping ring or damping block. This step is to ensure that the damping ring or damping block can still have a good fit with the gear or gear ring after long-term operation, and to reduce the electrochemical corrosion of the gear or gear ring.

[0021] Furthermore, in step seven, if the modal analysis frequency does not meet the requirements, repeat steps three through six, that is, change the slot position of the three-dimensional model of the gear or gear ring, remake the three-dimensional model of the damping ring or damping block and assemble it into the three-dimensional model of the gear or gear ring, and repeat the modal analysis verification.

[0022] Furthermore, in step eight, the number of damping rings or damping blocks is adjusted based on the processing and trial production of the gears or gear rings. This step is to ensure the processing progress of the gears or gear rings while avoiding waste caused by the inability to assemble the processed damping rings or damping blocks due to adjustments in the slotting position caused by modal testing.

[0023] Furthermore, in step nine, modal testing is performed using the ANSYS finite element method to verify the reduction in operational vibration. This step aims to verify the consistency between the finite element analysis results and the modal test results of the actual gears and gear rings, and to provide a reference for the modal test results in subsequent batch processing of gears and gear rings.

[0024] Furthermore, the surface roughness of the groove is Ra1.6. This step is to ensure that the damping ring or damping block can still have good fit with the grooved position after multiple disassembly and assembly, or when replacing with a new damping ring or damping block, thus ensuring good repairability of the gear or gear ring.

[0025] The beneficial effects of this invention are:

[0026] The method of this invention can reduce harmful operating vibrations of gears or gear rings without altering their original structure, without adding extra weight, and is repeatable, allowing for repeated improvements based on modal test results after each adjustment to achieve the optimal effect in reducing harmful operating vibrations. Vibration damping rings and blocks can be used for static or dynamic balancing to remove weight, and can be replaced when balancing fails or repairs are needed, thus reducing the difficulty of static and dynamic balancing adjustments and maintenance of large gears or gear rings. Attached Figure Description

[0027] Figure 1 This is a flowchart of the method of the present invention;

[0028] Figure 2 This is a schematic diagram of the bevel gear slotting in Example 2;

[0029] Figure 3 This is a schematic diagram of the vibration damping ring in Example 2;

[0030] Figure 4 This is a schematic diagram of the installation of a vibration damping ring at the slotted position of the bevel gear in Embodiment 2. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention.

[0032] Example 1: Figure 1 This is a schematic diagram of an embodiment of the method for reducing the working vibration of gears or gear rings provided by the present invention. The specific implementation is as follows:

[0033] (1) Collect the vibration frequencies of the helicopter transmission system and the whole machine.

[0034] (2) Based on the design parameters of the gears or gear rings of the helicopter transmission system, model them using CATIA / UG and other modeling software, and export them as igs, stp or prt formats for subsequent modal analysis. Use the ANSYS finite element method to perform modal analysis on the three-dimensional model of the gear or gear ring and obtain the first four modal frequencies.

[0035] (3) Based on modal analysis, determine the vibration frequency closest to the transmission system or the whole machine. Modify the three-dimensional digital model of the gear or gear ring, and select the gear spokes, the inner and outer diameters of the gear ring, or the gear weight reduction hole for grooving, with priority given to the annular groove with the largest diameter. If the annular groove is not feasible to process, multiple evenly distributed strip grooves or fan-shaped grooves on the same pitch circle can be selected.

[0036] (4) Design and manufacture a three-dimensional model of the vibration damping ring or vibration damping block according to the groove size.

[0037] (5) Select materials for damping rings or damping blocks. Multiple materials can be selected based on the actual material inventory.

[0038] (6) Assemble the three-dimensional model of the damping ring or damping block into the three-dimensional model of the gear or gear ring, and use the ANSYS finite element method to perform modal analysis to verify the reduction of working vibration.

[0039] (7) If the modal analysis frequency does not meet the requirements, change the slot position of the three-dimensional model of the gear or gear ring, remake the three-dimensional model of the damping ring or damping block and assemble it into the three-dimensional model of the gear or gear ring, and re-perform modal analysis verification.

[0040] (8) Produce and manufacture the gears or gear rings and damping rings or damping blocks that have completed modal analysis.

[0041] (9) Install the damping ring or damping block onto the gear or gear ring and perform modal testing to verify the reduction of working vibration.

[0042] (10) Perform static or dynamic balancing according to the design requirements of the gear or gear ring. The balancing can be achieved by removing material from the damping ring or damping block.

[0043] Example 2

[0044] A bevel gear used in a helicopter transmission system may experience harmful vibrations at an operating speed of 420 r / min. To mitigate the effects of this vibration, the bevel gear is modified.

[0045] Modal analysis was performed on the existing bevel gear model, and the slot was selected at the gear rim. The damping ring was chosen to be made of steel wire, a material similar to that of the bevel gear. Modal analysis verified that the operating vibration was far from the harmful vibration frequency. Figure 2 This document contains design drawings for the slotted gear and the vibration damping ring. The vibration damping ring features an opening for easy installation.

[0046] A damping ring mounting groove was machined onto the existing bevel gear, with a surface roughness of Ra1.6. The modified gear underwent corresponding supplementary surface treatment according to the design drawings.

[0047] Design and assemble the vibration damping ring. After assembly, conduct tests on the first four modal frequencies. After testing, perform static balancing and weight removal according to the design drawings.

Claims

1. A method for reducing the operating vibration of gears in a helicopter transmission system, characterized in that, Using a three-dimensional model of the gear or gear ring and finite element method, the first four modal frequencies of the gear or gear ring are calculated. Based on the gear structure, slots are cut into the gear or gear ring during static or dynamic balancing. Vibration damping rings or blocks are installed at the slots, followed by modal testing. The vibration is relatively reduced by adjusting the vibration damping rings or blocks. The specific steps of the method are as follows: Step 1: Determine the vibration frequencies of the helicopter's transmission system and the entire aircraft; Step 2: Using the 3D model and finite element method, calculate the first four modal frequencies of the gear or gear ring, and determine whether the calculation results are the same as or similar to the vibration frequencies of the helicopter transmission system and the whole aircraft. Step 3: Select the slotting position based on the frequency determination result and the gear ring structure; Step 4: Design vibration damping rings or blocks according to the gear or gear ring structure; Step 5: Select the material for the damping ring or damping block; Step 6: After installing damping rings or damping blocks at the slotted positions of the gear or gear ring 3D model, perform modal analysis again; Step 7: If the modal analysis frequency does not meet the requirements, repeat steps 3 to 6. If the modal analysis frequency meets the requirements, proceed to step 8. Step 8: After the modal analysis frequency meets the requirements, perform trial production of gears or gear rings and damping rings or damping blocks; Step 9: Install the damping ring or damping block onto the gear or gear ring, and perform modal testing on the gear or gear ring after assembling the damping ring or damping block to verify the reduction of working vibration. Step 10: Perform static or dynamic balancing on the gear or gear ring. During the static or dynamic balancing process, adjust the weight of the damping ring or damping block to reduce the working vibration of the gear or gear ring.

2. The method for reducing the operating vibration of gears in a helicopter transmission system according to claim 1, characterized in that, In step two, the gear or gear ring is modeled using CATIA / UG modeling software.

3. The method for reducing the operating vibration of gears in a helicopter transmission system according to claim 1, characterized in that, In step three, before static or dynamic balancing of the gear, grooves are made on the gear spokes, the inner and outer diameters of the gear ring, or the weight reduction holes of the gear, according to the gear structure.

4. The method for reducing the operating vibration of gears in a helicopter transmission system according to claim 1, characterized in that, Step five involves selecting the same material as the gear or gear ring as the machining material for the damping ring or damping block.

5. The method for reducing the operating vibration of gears in a helicopter transmission system according to claim 1, characterized in that, In step seven, if the modal analysis frequency does not meet the requirements, repeat steps three through six, that is, change the slot position of the three-dimensional model of the gear or gear ring, remake the three-dimensional model of the damping ring or damping block and assemble it into the three-dimensional model of the gear or gear ring, and repeat the modal analysis verification.

6. The method for reducing the operating vibration of gears in a helicopter transmission system according to claim 1, characterized in that, In step eight, the number of damping rings or damping blocks is adjusted according to the processing and trial production of the gears or gear rings.

7. The method for reducing the operating vibration of gears in a helicopter transmission system according to claim 1, characterized in that, In step nine, modal testing is performed using the ANSYS finite element method to verify the reduction in operational vibration.

8. The method for reducing the operating vibration of gears in a helicopter transmission system according to claim 1, characterized in that, The surface roughness of the grooved area is Ra1.6.

Images