Low-vibration-noise water-lubricated bearing bush with bionic snake scale microstructure and preparation method of low-vibration-noise water-lubricated bearing bush

Abstract

The invention relates to a low-vibration noise water-lubricated bearing bush with a bionic snake scale microstructure and a preparation method thereof, and aims to solve the problem of abnormal friction noise of ship water-lubricated rubber and medium carbon steel bearings in a complex seawater environment. The invention provides a method for preparing a bionic snake-shaped scale skin micro triangular array on the surfaces of rubber and medium carbon steel materials to inhibit friction noise, which mainly comprises the following steps of: 1, performing feature extraction on a snake belly scale skin microstructure, including parameters such as shape, arrangement mode, feature size and the like of the microstructure; 2, performing similarity simplification on the extracted snake abdomen scale epidermis microstructure; and 3, copying the simplified bionic snake scale microstructure to the surfaces of water-lubricated bearing rubber and medium carbon steel bearing bushes through laser etching and hot stamping technologies. The surface of the micro-triangular array displays the indentation modulus and the friction force which are consistent with the topographic features of the micro-triangular array and change periodically, so that viscous sliding is favorably interrupted, friction noise is inhibited, and the micro-triangular array has important significance on ship concealment and safety.

Description

Technical Field

[0001] This invention relates to the field of water-lubricated bearing bush manufacturing, specifically to a low-vibration-noise water-lubricated bearing bush with a biomimetic snake-scale microstructure and its preparation method. Background Technology

[0002] Water-lubricated rubber stern bearings are water-lubricated hydrodynamic sliding bearings that use rubber as the support and friction surfaces. As a crucial component of modern ship propulsion systems, their lubrication performance, load-bearing capacity, dynamic characteristics, and service life directly determine the safety, stability, and reliability of the ship. Water-lubricated rubber bearings offer advantages such as simple structure, low friction and wear, and environmental friendliness, and rubber materials possess strong buffering and vibration damping properties. However, due to the relatively low viscosity of water, the liquid film thickness is relatively thin under the same load. This makes it difficult to form an effective lubricating water film during start-up, shutdown, and low-speed, heavy-load conditions, resulting in extremely poor lubrication of the stern bearing. This can even lead to direct contact between the shaft and the rubber bearing surface, resulting in stick-slip phenomena, ultimately causing abnormal frictional vibration and radiated noise, producing a whistling sound. Furthermore, the increased coefficient of friction causes severe abnormal wear on the rubber bearing, affecting the reliability and service life of the water-lubricated bearing, and consequently reducing the ship's acoustic stealth capabilities. Therefore, reducing the frictional vibration and abnormal radiated noise of water-lubricated bearings has significant practical value and engineering significance for enhancing ship safety, stability, and acoustic stealth performance.

[0003] The abnormal frictional vibration and noise of water-lubricated rubber bearings are related to various factors, including bearing material and structural characteristics, bearing structure, adhesion at the friction pair interface, and lubrication performance. They are also influenced by external factors such as specific pressure, speed, temperature, shaft condition, and lubrication medium. Currently, to improve the surface lubrication environment of water-lubricated bearings under low-speed conditions and reduce surface frictional vibration noise, two main approaches are used: First, modifying the water-lubricating material by adding fillers to optimize its lubrication performance and improve its wear resistance, while ensuring good vibration and noise reduction performance. While adding lubricants to improve rubber lubrication performance or optimizing the damping capacity of rubber materials can effectively reduce frictional vibration, these methods can only alleviate frictional noise under certain test conditions and cannot completely eliminate it from the inherent properties of rubber. Second, designing a regular and orderly surface texture on the surface of the water-lubricating material and optimizing the bearing surface contact state can improve the bearing surface lubrication characteristics and reduce the generation of abnormal frictional noise.

[0004] Currently, a universal method for eliminating abnormal frictional noise on rubber material surfaces remains lacking. To address the practical engineering challenge of abnormal frictional noise frequently occurring in rubber under specific operating conditions, researchers have demonstrated that adding lubricants to improve rubber lubrication or optimizing the damping properties of rubber materials can effectively reduce frictional vibration. However, these methods can only alleviate frictional noise under certain test conditions and cannot completely eliminate it from the inherent properties of rubber. Customizing surface morphology, such as roughness or embedding micro / nanostructures, may offer a new approach to suppressing frictional noise. Considering that frictional noise is generated by the frictional behavior of the contact interface, it would be feasible to suppress the frictional noise of nitrile rubber by modulating interfacial friction through snake-scale microstructures. Meanwhile, studies have also shown that array-textured surfaces similar to the patterns on snake belly scales can suppress frictional noise, indicating that the microfiber structures on snake belly scales have great potential to reduce the frictional noise of nitrile rubber. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a low-vibration and low-noise water-lubricated bearing bush with a biomimetic snake scale microstructure and its preparation method, in response to the above problems and requirements.

[0006] To solve the above technical problems, the present invention adopts the following technical solution: A biomimetic snake-scale microstructure low-vibration and noise water-lubricated bearing bush and its preparation method are disclosed. The method involves using a bearing bush strip forming mold and employing a hot-pressing method to process the biomimetic snake-scale microstructure onto the surface of a nitrile rubber-based bearing bush strip, resulting in a water-lubricated bearing bush strip with the biomimetic snake-scale microstructure. Multiple water-lubricated bearing bush strips with the biomimetic snake-scale microstructure are then assembled to obtain a water-lubricated bearing bush with the biomimetic snake-scale microstructure. The biomimetic snake-scale microstructure comprises a uniform array of micro-triangles arranged parallel to the axial direction of the bearing bush strip. Each micro-triangle array includes multiple raised micro-triangle blocks. Each micro-triangle block is an isosceles triangle with its base perpendicular to the bearing bush strip. All micro-triangle blocks have the same apex orientation. The base of each isosceles triangle is 70-90 μm, the height is 110-130 μm, the thickness of each micro-triangle block is 10-12 μm, and the spacing between adjacent micro-triangle blocks is 10-12 μm.

[0007] Furthermore, the bearing bush strip forming mold includes an upper mold and a lower mold. The upper mold is provided with a boss, and the surface of the boss is provided with a reverse structure of biomimetic snake scale microstructure.

[0008] A method for preparing a water-lubricated bearing bush with a biomimetic snake-scale microstructure includes the following steps: Step 1: Heat the upper and lower heating plates of the precision hot pressing tester to 130-180℃, preheat the mold for more than 10 minutes, and then remove it. Step 2: Place the nitrile rubber sheet into the preheated mold container from the previous step, and then place the entire mold into a precision hot pressing tester. Pre-press it for 45-55 seconds at a heating temperature of 150-170℃ and a preset pressure of 5 MPa. Step 3: Use a precision hot pressing tester to hot press the nitrile rubber bearing strip at a heating temperature of 150-170℃ and a working pressure of 15 MPa for 35-45 minutes. Step 4: After the hot pressing time is reached, the upper and lower heating plates of the precision hot pressing test machine are cooled by cold water circulation. After the specified mold opening temperature of 70°C is reached, the upper and lower heating plates of the precision hot pressing test machine are separated, the mold is taken out, and the bearing strip and mold are cleaned after demolding to obtain a water-lubricated bearing bearing strip with a biomimetic snake scale microstructure. Step 5: Repeat steps 1-4 to obtain multiple water-lubricated bearing bush strips with biomimetic snake scale microstructures. Assemble and fix the multiple bush strips in sequence inside the copper sleeve to obtain a complete annular bearing bush.

[0009] A low-vibration, low-noise water-lubricated bearing with a biomimetic snake-scale microstructure includes multiple water-lubricated bearing bush strips with biomimetic snake-scale microstructures. The inner surface of the water-lubricated bearing bush strips is provided with biomimetic snake-scale microstructures. The biomimetic snake-scale microstructures include a uniform array of micro-triangles arranged along a direction parallel to the axial direction of the bush strip. The micro-triangle array includes multiple raised micro-triangle blocks. The micro-triangle blocks are isosceles triangles with their bases perpendicular to the bearing bush strips. All micro-triangle blocks have the same apex angle orientation. The base of the isosceles triangle is 70-90 μm, the height is 110-130 μm, the thickness of the micro-triangle blocks is 10-12 μm, and the spacing between two adjacent micro-triangle blocks is 10-12 μm.

[0010] Compared with the prior art, the present invention, by adopting the above technical solution, has the following advantages: To address the abnormal frictional noise problem of marine water-lubricated bearings in complex seawater environments, this invention provides a method for suppressing frictional noise by fabricating a biomimetic snake-scale-like micro-triangular array on the surface of rubber or medium-carbon steel materials. The main steps include: 1. Extracting features from the microstructure of the snake-scale-like surface, including parameters such as the shape, arrangement, and characteristic dimensions of the microstructure; 2. Simplifying the extracted snake-scale-like surface microstructure based on similarity; 3. Replicating the simplified biomimetic snake-scale-like microstructure onto the surface of the rubber or medium-carbon steel bearing bush of the water-lubricated bearing using laser etching and hot embossing techniques. The micro-triangular array surface exhibits periodically varying indentation modulus and frictional force consistent with its topographical features, which helps to interrupt stick-slip behavior and suppress frictional noise, and is of great significance for the stealth and safety of ships. Attached Figure Description

[0011] Figure 1This is a schematic diagram of the process for fabricating a water-lubricated bearing with a biomimetic snake-scale micro-triangular array. Figure 2 Figures (a) and (b) are schematic diagrams of the mold structure for preparing the biomimetic snake scale micro-triangular array designed in this invention; Figure (c) is a microscopic surface morphology of the mold observed using a scanning electron microscope. Figure 3 Figure (a) is a schematic diagram of the bearing strip structure, Figure (b) is a schematic diagram of the bearing structure, and Figure (c) is a microscopic three-dimensional morphology diagram of the bearing surface of the biomimetic snake scale micro-triangular array; Figure 4 Figure (a) shows a schematic diagram of stick-slip friction on a planar bearing and stable friction force on a microstructure bearing; Figure (b) shows the Fourier transform diagram of the planar bearing in the frequency domain; Figures (c) and (d) show the vibration results of the planar bearing and the bearing of the present invention in the time and frequency domains, respectively; Figure (e) shows the time-frequency diagrams of the noise generated by the planar bearing and the bearing of the present invention during frictional vibration; and Figure (f) shows the time-frequency diagram of the background noise when the sound level meter is working without frictional contact. Detailed Implementation

[0012] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0013] The present invention proposes a low-vibration, low-noise water-lubricated bearing bush with a biomimetic snake-scale microstructure and its preparation method, inspired by, for example, the following. Figure 1 The image shows a micro-triangular array of scales on the snake's abdomen.

[0014] like Figure 2-3 As shown, the method of the present invention includes the following steps: Step 1: The molted ventral scales of the Chinese cobra (Naja atra) were cut into small pieces and characterized and analyzed for their microstructure using scanning electron microscopy. Before imaging, a thin layer (approximately 10 nm) of gold was sputtered onto the surface of the snake scale samples to increase their conductivity.

[0015] Step 2: Based on the microfiber structure of the snake scale surface characterized by scanning electron microscopy, extract the features of the structure and record the size, height, gap and arrangement of the microfiber protrusions.

[0016] Step 3: Mimicking the finger-like microfiber structure on snake scales, based on the characteristic dimensions of the microfiber structure extracted in the previous step, simplify it into a uniformly arranged array of micro-triangular structures. The micro-triangular array size of the snake's belly scales is magnified 20 times proportionally, determining the characteristic dimensions of the micro-triangular array on the surface of the water-lubricated bearing bush as follows: length and width approximately 120 μm and 80 μm, with a gap of approximately 10 μm. The orientation of the microstructure is: the micro-triangular blocks are uniformly arranged and parallel to the axial direction; specific dimensions are shown in [reference needed]. Figure 1 The upper mold diagram.

[0017] Step 4: Based on the existing scaled-down test bench for simulating the stern bearing shafting of ships, design a scaled-down bearing that is compatible with it. The bearing parameters are: bearing inner diameter of 80 (+0.15~+0.40) mm, bearing outer diameter of 110 (+0.037~+0.059) mm, and bearing length of 320±0.5 mm.

[0018] Step 5: The mold consists of an upper mold and a lower mold. A reverse structure (female mold) with a biomimetic snake-scale microstructure, namely an array of micro-triangular pits, was designed and manufactured on the surface of the Stavax ESR steel upper mold using laser etching technology. The depth of the micro-pits is approximately 10 μm. Then, a layer of kerosene is sprayed onto the surface of the mold's microstructure to prevent corrosion from oxygen and water in the air. The lower mold has a groove with a depth of 20 mm to hold the unprocessed bearing strip, and plugs on both sides are used to fix the bearing strip.

[0019] Step 6: First, heat the upper and lower heating plates of the precision hot pressing tester to 160°C and preheat the mold for 10 minutes, then remove the mold.

[0020] Step 7: Place the three layers of rubber sheets into the preheated mold container, and then place the entire mold into a precision hot pressing tester and pre-press it for 50 seconds at a heating temperature of 160°C and a preset pressure of 5 MPa.

[0021] Step 8: Use a hot pressing tester to hot press the nitrile rubber bearing strip at a heating temperature of 160℃ and a working pressure of 15 MPa for 40 minutes.

[0022] Step 9: After the hot pressing time is reached, the precision hot pressing testing machine is cooled by circulating cold water through the upper and lower heating plates. Once the specified mold opening temperature of 70℃ is reached, the upper and lower heating plates of the testing machine are separated, and the mold containing the water-lubricated bearing bush strip is removed. After demolding, the bush strip and mold are cleaned with acetone to remove residual material, dust, etc. This yields a water-lubricated bearing bush strip with a biomimetic snake-scale micro-triangular array.

[0023] Step 10: Repeat the above steps to obtain 8 water-lubricated bearing bush strips with a biomimetic snake scale micro-triangular array.

[0024] Step 11: Machining mounting holes and positioning grooves on the bearing bush and the copper sleeve respectively. The bearing bush with its biomimetic microstructure is then mounted on the bearing copper sleeve via the positioning grooves and fastening bolts. Considering the shrinkage and expansion rates of nitrile rubber, the bearing bush gap is set to 0.4 mm. The steel plate in the middle of the bearing bush is 3 mm thick, with three bolt holes designed in the center, and is fastened to the copper sleeve with bolts. This results in a water-lubricated bearing with a biomimetic snake-scale micro-triangular array. Furthermore, considering the potential for seawater corrosion, the bearing bush is made of bronze, including gunmetal (88% copper, 10% tin, and 2% zinc) or a 70-30 zinc-nickel-copper alloy.

[0025] like Figure 4 As shown, friction, vibration and noise tests were conducted on the manufactured planar bearing and microstructure bearing water-lubricated bearings. It can be seen that the bearing of the present invention can significantly reduce the stick-slip behavior of water-lubricated bearings and suppress friction noise.

[0026] The above description provides examples of the preferred embodiments of the present invention. Parts not detailed herein are common knowledge to those skilled in the art. The scope of protection of the present invention is determined by the claims. Any equivalent modifications based on the technical teachings of the present invention are also within the scope of protection of the present invention.

Claims

1. A biomimetic snake scale microstructure low vibration noise water-lubricated bearing bush and its preparation method, characterized in that , The bionic snake scale microstructure water-lubricated bearing bush bar is obtained by using a bearing bush bar forming die, adopting a hot pressing method to process bionic snake scale microstructures on the surface of a nitrile rubber-based medium-carbon steel bush bar, and assembling multiple water-lubricated bearing bush bars with the bionic snake scale microstructures.

2. The method of manufacturing a water-lubricated bearing bushing with biomimetic scaly microstructure according to claim 1, characterized in that, The bearing bush bar forming die comprises an upper die and a lower die, and the upper die is provided with a boss, and the surface of the boss is provided with a reverse structure of the bionic snake scale microstructure.

3. The method of manufacturing a water lubricated bearing bushing with biomimetic scaly microstructure according to claim 1, characterized in that, The method comprises the following steps: Step 1: heat the upper and lower heating plates of a precision hot press testing machine to 130-180℃, and preheat the die for more than 10 minutes and then take it out; Step 2: place the nitrile rubber sheet into the die container preheated in the previous step, and then place the entire die into the precision hot press testing machine, and pre-press at a preset pressure of 5 MPa for 45-55 seconds at a heating temperature of 150-170℃; Step 3: hot-press the nitrile rubber bush bar at a working pressure of 15 MPa at a heating temperature of 150-170℃ by using the precision hot press testing machine, and the hot-pressing time is 35-45 minutes; Step 4: after the hot-pressing time is reached, the precision hot press testing machine is used to cool the upper and lower heating plates by circulating cold water, and after the specified mold opening temperature of 70℃ is reached, the upper and lower heating plates of the precision hot press testing machine are separated, the die is taken out, and after demolding, the bush bar and the die are cleaned to obtain the water-lubricated bearing bush bar with the bionic snake scale microstructure; Step 5: repeat steps 1-4 to obtain multiple water-lubricated bearing bush bars with the bionic snake scale microstructure, and sequentially assemble and fix the multiple bush bars in the copper sleeve to obtain a complete annular bush.

4. A biomimetic snake scale microstructure low vibration noise water lubricated bearing bush and its preparation method, characterized in that, The bionic snake scale microstructure water-lubricated bearing bush bar comprises a plurality of water-lubricated bearing bush bars with the bionic snake scale microstructure, and the inner side surface of the water-lubricated bearing bush bar with the bionic snake scale microstructure is provided with the bionic snake scale microstructure.

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