Plain Bearings Research Articles

A Review of the Research on the Influencing Factors of Lubrication Performance for Sliding Bearings

Background: Sliding bearing is a kind of bearing that works under sliding friction, which has the characteristics of stable operation, safety and reliability, and is noiseless. With the technological progress of the machinery industry, modern machinery and equipment is developing in the direction of high speed and heavy load, its power is getting higher and higher, and the working environment is getting worse, so plain bearings are more and more widely used. Objective: In order to improve the lubricating performance of sliding bearings, the influencing factors of the lubricating performance of sliding bearings are summarized and commented on. Methods: The research progress and achievements at home and abroad are summarized from three aspects: influencing factors of lubrication performance of radial sliding bearings, thrust sliding bearings, and influencing factors of lubricating oil on lubrication performance of sliding bearings, which provides reference for the future development of sliding bearings. Results: The study discusses the experimental method, simulation process, and experimental results of the factors affecting the lubrication performance of sliding bearing. Conclusion: The texture, deformation, surface morphology of oil cavity, eccentric load, and flow state of sliding bearings all affect the lubricating performance of sliding bearings, and lubricating oil also affects the lubricating performance of sliding bearings.

PROJECT CONCEPTION OF CAE-SYSTEM FOR WEAR ANALYSIS OF FRICTION BEARING UNDER CONDITIONS OF SHAFT AND LINER AXIS MISALIGNMENT

Modelling of wear processes is an important stage in the design of mechanisms. Such virtual studies allow predicting the service life of components and the machine as a whole. Modern algorithms of CAE-systems allow performing such analysis with high accuracy and taking into account not only material and operating conditions of the mechanism, but also errors that occurred during the manufacturing and assembly of a particular part. These parts require high requirements to the accuracy of manufacturing and assembly, but within the tolerances of the fields errors of mutual positioning are still allowed, which in turn can significantly affect the service life of the mechanism. Therefore, the task of modeling the wear process of the shaft and sleeve in conditions of mutual misalignment of the axes is relevant. Such sliding pairs exist in almost all machines, including car engines, power generation turbines, etc. In this article it is offered to use the module-integrated approach for modeling of wear processes in tribotechnics, providing use of CAE-systems for definition of functioning conditions of friction units as a system core, and construction of separate modules which in this or that degree are integrated into existing CAE systems. to define values of wear of elements of friction pairs that allows to consider mutual influence of wear and change of functioning conditions in the course of operation. The practical implementation of the module-integrated approach is shown by the example of solving the problem of radial plain bearings wear during the misalignment of the shaft and bush axes in the ANSYS environment. The module of representation of multidimensional matrixes of static or dynamic data, providing essential increase in speed of data processing and quality level of the further analysis of the visualized information from any subject area, is developed.

Tensile and Fracture Behavior of Bi-Containing Alloy Sintered on SAE 1010 Steel Sheet

The purpose of this study is to investigate the fractural behavior of lead (Pb)-free material containing bismuth (Bi) that was developed to replace the Pb included in sintered copper (Cu)-based alloy for plain bearings. Mechanical properties and microstructure of two different sintered Cu-based alloys (CuSn10Pb10 and CuSn10Bi7) were compared and analyzed. Under tensile load, a CuSn10Pb10 layer is decomposed into powder and changed to form pores leading to an expansion. Therefore, even after tensile elongation, the matrix itself did not stretch, with no work hardening. However, in the case of CuSn10Bi7, a Bi kept its original shape, resulting in it being the same length as the steel plate, where the hardness and strength increased due to the effect of work hardening. These results suggested that the performance of the alloys was different under a high tensile load, where plain bearings usually undergo tensile deformation.

Investigation of the possible applications for microtextured rolling bearings

The application of microdimple-textured surfaces for rolling bearings is not very common but can be beneficial for various usage scenarios. In contrast to the applications for plain bearings or cylinder running surfaces, however, surface patterns for rolling bearings only offer advantages under certain conditions. For example, for use with start-stop cycles, in mixed lubrication conditions, or under sliding conditions in a bearing as well as on a roller—bearing flange contact, friction can be reduced with the targeted use of microtextures. The geometry of the microtextures must be chosen so that individual dimples fit in the contact area between the ball or roll and the bearing surface in order to act as a reservoir for the lubricant. First applications for microtextured angular contact ball bearings under oscillating movement conditions proved friction reducing effects under reciprocating motion. In this case the microtextures served as lubricant reservoirs. The idea is transferred to the sliding contact for tapered roller bearings; it is investigated whether the measured reductions in friction are due to the microtextures serving as lubricant reservoirs or whether there is even a positive hydrodynamic effect caused by the microtextures. By means of a calculation approach as well as some exemplary test rig measurements, the behavior for microtextured tapered roller bearings is investigated.

Evaluation of wear mechanism between TC4 titanium alloys and self-lubricating fabrics

Self-lubricating spherical plain bearings are important product components in the aerospace industry. With technological advances, the limitations of steel self-lubricating spherical plain bearings with high quality but poor corrosion resistance became quite evident. The preparation of self-lubricating spherical plain bearings made of titanium alloys is of great interest. In general, titanium alloys have poor tribological properties as well as unsatisfactory tribological performance when they rub with soft self-lubricating fabrics. To understand the wear mechanism of TC4 titanium alloys, half-ring wear tests were conducted between TC4 titanium alloys and self-lubricating fabrics under different pressures and swing frequencies, namely, 50 and 100 MPa, and 0.2 and 0.4 Hz, respectively. The corresponding results showed that the friction coefficients (COFs) between TC4 titanium alloys and self-lubricating fabrics greatly fluctuated in the range of 0.1–0.25. The main wear form of titanium alloys was a combination of abrasive wear and adhesive wear, and the accumulated debris generated during the friction process was the main cause of surface damage of TC4 titanium alloys. The accumulated debris tended to increase with increasing pressure and swing frequency. The debris scratched and made large grooves in titanium alloy surfaces and aggravated the wear of self-lubricating fabrics, which led to severe fibre breakage. This paper describes a novel wear mechanism of accumulated debris and offers a solid theoretical foundation for the application of titanium alloys in the field of self-lubricating spherical plain bearings.

Influence of an outer ring end offset on the service life and eccentric wear defects of self-lubricating spherical plain bearings

Improving the service life of self-lubricating spherical plain bearings is important due to the wear failure of the self-lubricating layer is considered as the primary reason for their service life decreases. Currently, there remains a lack of research on the influence of the forming accuracy of radial symmetry on bearing service life. This study investigated the relationship between the forming accuracy of self-lubricating spherical plain bearings and bearings’ life, by proposing the concept of the outer ring end offset. Based on the influence of the offset on the contact stress and strain of the bearing, the range of reasonable offset was analyzed. The correctness of the range of offset was verified by bearing friction tests, and the wear mechanism of the bearing eccentric wear phenomena was described. Results show that the forming accuracy of the outer ring is an essential factor that affects bearing service life. The outer ring end offset can be used as a key indicator of forming accuracy. Considering the GE15DE1TK self-lubricating spherical plain bearing as an example, the outer ring end offset with an over-extrusion bearing should be less than 0.05 mm. However, the required offset for an insufficient-extrusion bearing does not easily produce eccentric wear defects even with an offset of 0.08 mm. This paper provides a new idea and indicator for improving the service life of self-lubricating spherical plain bearings.

Определение теплового состояния элементов турбокомпрессора поршневого двигателя

The power boost of heat engines is conditioned by the increase in the load on all its elements and related units. The turbocharger is one of the most common units that provide the power boost of a heat engine. The reliability of the turbocharger and its tribo-couplings guarantees the stable operation of not only it, but also the machine as a whole. An increase in the rotor speed leads to an increase in the thermal loading of the turbocharger elements. In this regard, timely assessment of the thermal state of the tribocoupling components, temperature distribution over the shaft, housing and other elements of the turbocharger is an urgent task. An algorithm for calculating heat transfer between the elements of a turbocharger has been developed, and an assessment of the heat load of radial multilayer plain bearings of a flexible asymmetric rotor has been made. The simulation was carried out in the ANSYS Fluent software package. The experimental data of the manufacturing plant were used as boundary conditions. The results of the calculation are given: the distribution of thermal fields in the turbocharger housing and the temperature in the area of ??the turbine and compressor plain bearings. Dependences of temperatures in the bearing area on the rotor speed are obtained. The calculation results were verified by comparing the temperatures in the turbine and compressor plain bearings with the data given in the publications of other authors. The temperature values in the outer and inner layers of the bearing were the initial data for calculating the dynamics of the turbocharger rotor, taking into account the thermal deformations of the tribocouple elements. The results of the research will be used to assess the stability of the movement of the rotor, the failure-free operation of the bearing assembly, as well as the reliability and durability of the turbocharger as a whole.

Using Composite Materials with Magnesium Matrix for Plain Bearings

Using Composite Materials with Magnesium Matrix for Plain Bearings

Function Integration in Additive Manufacturing: Design and Realization of an LPBF Built Compressed Air Motor.

We present a compressed air motor, completely built by laser powder bed fusion. To highlight the fully functional integration by additive manufacturing, the rotor, stator, bearings, turbine, gas inlet and outlet were all built in a single print job. The material used was Inconel 718, and the motor was 44 mm tall and 12 mm in diameter. With the rotation axis of the motor in print in the direction of the laser powder bed fusion process, no build supports are needed, and thus the rotor and stator are fully moveable against each other. Plain bearings were used to position the rotor inseparably inside the stator, with a bearing gap of 0.2 mm, resulting in stable rotation. The idle rotation speed of the motor was measured with a digital laser measuring device as a function of air pressure and inlet size. With linear behavior between the rotation speed and gas pressure of up to 5.5 bar, the motor can be easily controlled. With varying gas inlet sizes, the idle rotation speed of the compressed air motor is also varied. A maximum rotation speed of 90,000 rpm was achieved at 1.5 mm gas inlet size and 3 bar gas pressure.

Влияние капролоновых дейдвудных подшипников на рабочее состояние гребного вала

The paper considers the conditions for reliability of the ship rudder-propeller complex, whose operation depends on the status of the stern bearings of the ship shafting. Stern bearings are plain bearings located in the vessel's stern tube, they support the propeller shaft of the ship’s shafting. The stern tube is similar for all types of ships, inside which there are located the bearings and a sealing device that prevents ingress of outboard water inside the vessel. It is pointed out that the stern bearings made of caprolone have certain advantages over other traditionally used materials. The numerical values of the main parameters of caprolone stern bearings are presented on the basis of normative and regulatory documents. It is stated that physical and mechanical properties of caprolone in almost all respects are higher than those of other materials currently used for this purpose. Along with strength and high load capacity, caprolone has a low friction coefficient (0.04-0.08). To study the contact of the propeller shaft with the stern bearing there is considered a design diagram (a beam resting on an elastic base with a stiffness coefficient k). The stiffness coefficient of the elastic foundation characterizes the elastic and mechanical properties of the stern bearing. It is proved that caprolone used in stern bearings allows increasing the reliability of the ship’s shafting by full contact with the propeller shaft, reducing vibration and noise, resisting the erosion wear, and increasing safety

Аналіз роботи гідростатичного підшипника на перехідних режимах

The design of reliable rotor supports for modern high-speed machines is associated with the solution of many complex problems, both theoretical and experimental. Experimental studies play an important role in the system of scientific research and allow improvement and refine mathematical models and the application of numerical methods for their implementation. Experimental studies are usually selective and therefore require careful preparation. The task was set to investigate the characteristics of a hydrostatic bearing in the starting and braking modes. A program of experimental studies of the behavior of a shaft on hydrostatic bearings for the most difficult operating conditions has been developed. The advantages of hydrostatic bearings are given compared with other types of plain bearings, as well as compared with rolling bearings. The effectiveness of hydrostatic bearings is shown, compared with other types of bearings, for modern high-speed machines, in which there is an increase in vibration overloads and vibration displacements. Hydrostatic bearings have proven themselves in all operating modes, including transient ones. A description of the experimental setup for the study of transient modes of operation of the shaft on hydrostatic bearings is given. Studies of the transient modes of operation of the shaft on hydrostatic bearings were conducted at various values of the pressure of the working fluid supply, residual unbalance, as well as various values of the diameter of the hydrostatic bearing. To identify the movement of the rotor on hydrostatic bearings, the values of the amplitudes of oscillations during stationary (steady) movement of the rotor are also presented. It is shown that the comparison of the oscillation amplitudes of the rotor on hydrostatic bearings with a diameter of 0.06 m for the cases of non-stationary and stationary modes of its operation during the acceleration of the amplitude of oscillations in the entire range of rotational speeds is slightly lower (by about 15…20 %) than in the case of a stationary mode of operation of the rotor. When the rotor slows down, the amplitude of the rotor oscillations at high speeds is somewhat larger (by about 7…9 %), and at low speeds it is less by 8…10 % than in the case of a stationary rotor operation. The small influence of the non-stationary nature of the rotor movement on the dynamic characteristics can be explained by its large mass.

Numerical model to predict wear of dynamically loaded plain bearings

Wear resistance of dynamic system components is a major challenge in aeronautics. According the usage of the aircraft, off-centred dynamic loads can appear on shafts when rotating bodies are unbalanced. In literature, most of the wear studies applied to plain bearing consider static loads centred in the contact area. This article presents a study on the wear of a plain bearing submitted to off-centred dynamic loads in order to look for a better mastering of service life of plain bearing for their usage in severe aeronautic conditions. Boussinesq's equations were used to compute the pressure distribution and Archard's law was used to calculate the wear. The wear coefficients of the running-in and stable wear stages were defined experimentally. The evolution over time of the maximum wear depth and the size of the contact zone were validated with experimental results. The perspective of this work is to feed digital twins of dynamic systems in order to predict wear according aircraft usage.

Investigation of Dry Sliding Friction Wear Behavior of CuSn11 Bronze Plain Bearing Applying Impregnated Graphite-Filled PTFE

Self-lubricating bearings are produced by using copper-based materials and solid lubricating polymer materials, which are widely used in industrial applications. Self-lubricating bearings have been developed to improve systems that do not have the possibility of continuous lubrication. This study describes the experimental investigation of tribological properties of graphite-filled polytetrafluoroethylene (PTFE) composites. First, the CuSn11 porous specimens were produced by powder metallurgy. The superior properties of bronze and PTFE were used to create the composite specimens. Solid lubricants, namely, pure PTFE and two different graphite-filled PTFE (PTFE + 10 wt% graphite and PTFE + 20 wt% graphite) mixtures were impregnated into pores of the bronze specimens using a spray coating method. Thus, bronze composite specimens with graphite-filled PTFE were obtained. Then changes in the friction coefficient and wear loss were achieved differently under three loads and sliding speeds with wear tests performed under dry test conditions. The results showed that the graphite additive reduced the friction coefficient and the wear loss. The lowest friction coefficient was obtained from the 20 wt% graphite-filled specimen under the lowest sliding distance (4500 m) and the highest load (70 N) test conditions. However, a 2.95% reduction in the friction coefficient and 16.28% reduction in the wear loss of PTFE + 10 wt% graphite specimen were detected compared to the 20 wt% graphite specimen, depending on the increase in sliding distance under the highest sliding distance (13,500 m) and the highest applied load (70 N) test conditions.

Preparation of a titanium alloy outer ring self-lubricating spherical plain bearing by a two-step extrusion forming process

Self-lubricating spherical plain bearings are a key component widely used in the aerospace field. The spherical plain bearing made of titanium alloy has a lighter weight and better corrosion resistance. To manufacture the outer ring of a self-lubricating spherical plain bearing with titanium alloy, a two-step extrusion forming process was proposed. Taking a GE15DE1TK spherical plain bearing as an example, the finite element simulation model of the forming process was established, the forming test was carried out, and the outer ring of a self-lubricating spherical plain bearing made by TC4 titanium alloy was successfully prepared. The results show that forming defects such as over extrusion and insufficient extrusion can be improved by optimizing the die structure, the size of the outer ring blank, and the lubrication conditions. The forming parameters for the GE15DE1TK spherical plain bearing are given. The prepared spherical plain bearing can be used directly without other processes to correct no-load rotational breakaway torque.

Innovative reducer for railroad switch drives and evaluation friction work on double sliding bearings

Railway transport plays a special role in the transportation of oil and petroleum products. Ensuring the speed and reliability of transportation is one of the important issues. The role of railroad switch electric drives in solving this problem is great. Package type «AN» reducer have a number of advantages over traditional ones. The article presents the features and the essence of increasing the technological and exploitational parameters of the transmission mechanism of railroad switches with the help of a new innovative package type «AN» reducer, developed at AzTU. An analysis of the work of friction on plain bearings used in package reducers, instead of keyed connections in traditional gearboxes, is given. The effectiveness of the use of package type «AN» reducers in the transmission mechanisms of railroad switch electric drives has been revealed. Keywords: railroad switch drive; mechanism; innovative; increase; reducer; reliability.

Modifikasi Mesin Pengupas Pinang Belah Kering Model Thresher

Modify the palm fruit thresher machine into a thresher model dry split betel nut peeler by testing the tool so that it can find out the constraints of the palm fruit thresher machine, and disassembling the components or parts to be modified, namely; cover, collection channel, blade and drive clutch. The cover is designed to function to be sturdy from the impact of areca nuts and is cylindrical. The reservoir channel is designed to allow the peeled betel nut to enter the drain pipe and the blower is in charge of blowing between the peeled betel nut and the seeds. The blade is designed to peel the dry split betel nut. The drive clutch is designed to function as a connector/breaker for the engine rotation to the shaft and plain concrete iron and bearings as a v-belt retainer. In the test with a capacity of 50 kg 1 day drying, peeled 40 kg and unpeeled 10 kg with an average time of 15 minutes is the best test. Therefore, we can conclude that the best peeling results from this dry split betel nut peeler machine are almost 80% peeled.

Hidrodinamik radyal kaymalı yataklarda yüzey pürüzlülüğünün sürtünme davranışları üzerindeki etkilerinin incelenmesi

In hydrodynamic plain bearings, parameters such as friction coefficient, oil film thickness, pressure distribution, oil flow, etc. are very important design criteria in terms of bearing design and optimum energy efficiency. In this study, in order to investigate the effects of surface roughness on bearing performance in hydrodynamic plain bearings, experiments were carried out at different loads and temperatures using two bearing envelopes with the same bearing material and with different surface roughness. As a result of the experiments, it was determined that the surface roughness was more effective especially in the boundary and mixed friction region than in the fluid friction region. It was determined that while the oil film formation ability decreased with increasing surface roughness, wear and power loss in the bearing increased.

Estimation of tribotechnical parameters of composite polymer with metal filler

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 The use of composition material based on the polyamide (caprolon) Ertalon 4.6 as an anti-friction material in the sliding units in the aviation industry is considered. Low carbon electrotechnical sheet steel 21864 of different concentrations was used as filler of composite material. The article presents the thermal calculation of plain bearings with polymer insert in different operating modes. It is determined that the addition of a metal filler to polyamide causes a temperature decrease in the friction zone due to the effective heat exchange from the shaft to the bearing housing. The article conducts a study of tribo-technical properties of the proposed composite material on installation PT-4C under sliding conditions according to the scheme “cylinder-plane”, as well as modeling of the support unit in the software complex DS SolidWorks. It has been experimentally determined that the addition of finely dispersed steel filler enhances the antifriction properties of the Ertalon 4.6 polymer and extends the temperature range of the composite insert performance. Increasing the filler concentration to 20% results in a reduction of the friction coefficient by an average of 3.6 times and an increase in the temperature range of composite material use to 100 °C. The load-bearing capacity of the composite material bushing is increased to 25 MPa at a 20% filler concentration respectively.
 The practical significance of the work lies in the analysis of the antifriction properties of the polymer with metallic filler in comparison with the polymer without filler, which will prove the effectiveness of the use of such polymers in friction units instead of non-ferrous metals (bronze, babbitt).

Influence of the 1% Ti content on microstructure, friction coefficient and contribution to the strengthening mechanisms in the Al20Sn1Cu alloy

Al–Sn alloys are widely used as plain bearings in several engineering applications, particularly in internal combustion engines, where the surface properties are the main properties determining the bearing performance and lifetime. Advanced combustion engines and hybrid systems demand the reduction of wear as well as an increase in loading capacity for plain bearings. Thus, new bearing alloys with improved strength and friction properties have to be developed. For this purpose, Al20Sn1Cu and Al20Sn1Cu1Ti (wt.%) ribbons were produced by single roller melt spinning at low speeds. The ribbons were subsequently bonded by co-rolling with Al with 99.9% purity. Microstructure characterization, hardness and wear tests were used to characterize the ribbons and the co-rolled ribbons. The melt-spun samples show that the microstructures of these alloys are composed of an α-Al matrix and homogeneously distributed β-Sn and γ−Al3Ti. The addition of Ti affects the microstructure by reducing the size of α-Al grains and by changing the distribution and size of Sn particles, resulting in increased hardness and a reduction of the friction coefficient.

Анализ работы опорных подшипников турбомашин на экологически чистых жидкостях

The subject of study in this article is the cost-effectiveness of the rotors of powerful turbines and their fire safety. Improvement of these indicators is possible by replacing oil lubrication systems with environmentally adaptive lubricants (EAL), in particular water or aqueous solutions. The main disadvantage of using water and other low-viscosity aqueous solutions for operating plain bearings is the lack of a hydrodynamic effect at low speeds of the rotor during start and stop of the turbine. The current study experimentally studies the possibility of replacing oil lubrication systems with EAL, in particular water or aqueous solutions. The objectives of the study: 1) to ensure that in the operating range of speeds and loads, the bearing operates in a stable hydrodynamic mode; 2) show that the use of a hydrostatic lifting system provides a liquid mode of friction in the range under study of loads and sliding speeds; 3) to determine the level of pressures at which the rotor rises. When solving this problem, the following methods were used. On the experimental stand, a full-scale radial bearing with babbitt filling of the working surface of the liner was tested. During the experiment, the following parameters were varied and measured: rotor speed, bearing load, lubricant consumption, working fluid temperature in front of and out of the bearing, water pressure (condensate) in the hydraulic system, pressure in the lubricating layer and chambers of the bearing. The main parameter by which the efficiency of the bearing was evaluated was the thickness of the lubricating layer of the working fluid. The following results were obtained. In the first stage, when the speed of the rotor is zero, the value of the pressure of the fluid supply, which ensures the emergence of the shaft. In the second stage, the dependence of the relative eccentricity on the shaft speed and the speed at which it is possible to turn off the rotor lifting system. Conclusions. In the investigated range of speed and loads, the bearing operated in a stable hydrodynamic mode. The use of a hydrostatic lifting system provided a liquid mode of friction in the range under study of sliding speeds (including starting and stopping the rotor). The temperature of the working surface of the bearing in a stable hydrodynamic mode depends little on the external load and sliding speed.