Surface Of Bushing Research Articles

The influence of volumetric electromechanical mandreling on the lead yield from the matrix material on the bronze bearing bushing surface

The data on the effect of electromechanical mandreling (EM) modes of rolled bushings made of Bronze-Tin-Zinc-Lead (BTZL) 4-4-2.5 on the lead yield from the matrix material to the work surface are given. As a result of an X-ray analysis, it was found that up to 13.3% of lead is eliminated from the matrix material to the bushing’s surface, filling all irregularities after machining, bringing the actual contact area to the contour one and significantly reducing contact stresses under loading, which serves as a reserve for increasing the movable joint’s durability, along with decreasing the friction torque in the joint when operating under ‘film’ starvation conditions.

Coverage trajectory planning for a bush trimming robot arm

AbstractA novel motion planning algorithm for robotic bush trimming is presented. The algorithm is based on an optimal route search over a graph. Differently from other works in robotic surface coverage, it entails both accuracy in the surface sweeping task and smoothness in the motion of the robot arm. The proposed method requires the selection of a custom objective function in the joint space for optimal node traversal scheduling, as well as a kinematically constrained time interpolation. The algorithm was tested in simulation using a model of the Jaco arm and three target bush shapes. Analysis of the simulated motions showed how, differently from classical coverage techniques, the proposed algorithm is able to ensure high tool positioning accuracy while avoiding excessive arm motion jerkiness. It was reported that forbidding manipulation posture changes during the cutting phase of the motion is a key element for task accuracy, leading to a decrease of the tool positioning error up to 90%. Furthermore, the algorithm was validated in a real‐world trimming scenario with boxwood bushes. A target of 20 mm accuracy was proposed for a trimming result to be considered successful. Results showed that on average 82% of the bush surface was affected by trimming, and 51% of the trimmed surface was cut within the desired level of accuracy. Despite the fact that the trimming accuracy turned out to be lower than the stated requirements, it was found out this was mainly a consequence of the inaccurate, early stage vision system employed to compute the target trimming surface. By contrast, the trimming motion planning algorithm generated trajectories that smoothly followed their input target and allowed effective branch cutting.

Radial Friction Bearing with a Fusible Coating in the Turbulent Friction Mode

This paper presents a method for forming an exact self-similar solution to the problem of hydrodynamic calculation for a radial friction bearing that operates using an electrically conductive liquid lubricant conditioned by the bearing bushing surface melt, taking into account the influence of pressure and temperature on the viscosity and electrical conductivity of the liquid lubricant under adiabatic conditions. The asymptotic solution of a system of differential equations taking into account boundary conditions on the surface of a bearing bushing $$r = - {\Phi (}\theta {\text{)}}$$ has been found in the form of a series in powers of small parameter K caused by the melt and by the rate of mechanical energy dissipation.

Effects of bushing profiles on the elastohydrodynamic lubrication performance of the journal bearing under steady operating conditions

The bushing profiles have important effects on the performance of journal bearing. In this article, the effects of plain profile, double conical profile, and double parabolic profile on the elastohydrodynamic lubrication of the journal bearing under steady operating conditions are investigated. The journal misalignment and asperity contact between journal and bushing surface are considered, while the modification of the bushing profiles due to running-in is neglected. Finite element method is used for the elastic deformation of bushing surface, while the numerical solution is established by using finite difference method and overrelaxation iterative method. The numerical results reveal that the double parabolic profile with appropriate size can significantly increase the minimum film thickness and reduce the asperity contact pressure and friction, while the maximum film pressure, load-carrying capacity, and leakage flow rate change slightly under steady operating conditions. This study may help to reduce the edge wear and prolong the service life of the journal bearing.

Experimental investigation for vibration reduction of surface-textured journal bearings

PurposeSurface texturing has emerged in the past two decades as a viable option of surface engineering, resulting in significant improvement in wear resistance and friction coefficient. The purpose of this study is to find the appropriate surface texture to reduce vibration and improve the stability of journal bearings.Design/methodology/approachMicro-dimples, evenly distributed in a square array, were selected as the texture pattern and formed on the lower surface of bush by the laser surface texturing technique. Experiments were carried out to evaluate the effects of micro-dimples under different depths, densities and distributions.FindingsThe results are summarized in the form of shaft center orbits, waterfall illustrations and Hilbert-Huang transforms. In the entire test, it was found that an optimum geometric and distributive range of micro-dimples exists, where vibration acceleration can be decreased at least 3dB and stability can be greatly improved.Originality/valueA majority of researchers devoted to studying on static characteristics, such as friction coefficient, load carrying capacity, pressure distribution and cavitation model. Besides, the influence of surface texture on stability of rotor-journal bearing system was rarely investigated and the recent examples can be found in Refs. (Ausas et al. 2007). However, a complete study of textured journal bearings has not been undertaken in the dynamic properties. Therefore, the purpose of this paper is to experimentally investigate the comprehensive effects of density, depth and distribution of micro-dimples on bearing vibration and stability.

Failure Analysis of an Automotive Bushing

The cause of a longitudinal fracture of an automotive bushing during the assembly process is presented in this study. On the basis of macroscopic inspection, scanning electron microscopy, energy-dispersive spectroscopy, microstructural examination, chemical analysis and hardness measurements, cleavage fracture was determined by the dominant fracture mode, and the fracture near the outer surface of the bushing was covered by impurities which is similar to the composition of the coating. Therefore, it is possible to infer that the crack existed before installation. In addition, the detailed metallurgical analysis demonstrates decarburization at the fracture surface due to a folding defect. In the process of assembly of bushing, the stress concentration and surface defect promoted the old crack propagation, finally, leading to the fracture of the bushing.

Numerical study of flows in axial compressors of aircraft gas-turbine engines

Design and adjustment of compressors at modern gas-turbine engines are based on the wide use of numerical analysis methods of a various level of complexity. Such approaches make it possible to analyze the alignment of joint operation of stages and to perform the required correction of geometrical parameters. The methods for calculating the 1D and 2D flow in compressors are distinguished by high flexibility, which allows the utilization of considerable experience in designing and experimental research. These methods are consequently in demand at all stages of the engine life cycle: when creating, adjusting, at operation.We present methods for the calculation of parameters and structure of current, as well as the summary characteristics of axial stages and multistage compressors. To solve a system of motion equations, we employed a matrix method, which makes it possible to apply small computation grids in a flow-through part of the compressor. The method is designed to numerically simulate the sub-, trans-, and supersonic flows in the flow-through part of axial compressor stages and multistage axial compressors at aircraft engines. The methods are implemented in the form of software complexes.The article reports certain results related to the verification of these complexes. We use data from experimental studies into various multi-stage compressors and high-head fan stages. We show a satisfactory agreement between calculated and experimental data over a wide range of modes of consumption and rotation frequency.The developed software package was used to improve the geometrical parameters for an axial multi-stage compressor, aimed at increasing the air flow rate through the compressor and enhancing the reserve of its gas-dynamic stability.Employing small computational grids made it possible to undertake a series of studies, previously available only for the calculation methods of spatial flow. We considered different variants for the execution of the bushing surface at a high-head fan stage. When analyzing the structure of flow in a stage, we show the change in the axial component of velocity in a blade-to-blade channel of the impeller along its axis.Development and application of the new methods of calculation will improve the quality of design of axial compressors and enhance competitiveness of the Ukrainian aircraft gas turbine engines.

Study of Dimple Effect on the Friction Characteristics of a Journal Bearing using Taguchi Method

The effect of producing dimples using chemically etched techniques or by machining process on the surface of a journal bearing bushing to reduce the friction using Taguchi method is investigated. The data used in the present analysis is based on the results obtained by the series of experiments conducted to study the dimples effect on the Stribeck curve. It is statistically proved that producing dimples on the bushing surface of a journal bearing has significant effect on the friction coefficient when used with light oils. Also it is seen that there is an interaction effect between speeds-load and load-dimples. Hence the interaction effect, which are usually neglected should be considered during actual experiments that significantly contributes in reducing the friction in mixed lubrication regime. The experiments, if were conducted after Taguchi method, then the number of experiments would have been reduced to half of the actual set of experiments that were essentially conducted.

Development of a hybrid computational/experimental framework for evaluation of damage mechanisms of a linked semiconstrained total elbow system

Long-term durability of total elbow arthroplasty (TEA) is a concern, and bearing wear or excessive deformations may necessitate early revision. The current study used experimental wear testing and computational finite element modeling to develop a hybrid computational and experimental framework for the evaluation of TEA damage mechanisms. Three Coonrad-Morrey (Zimmer-Biomet Inc., Warsaw, IN, USA) TEA implants were used for experimental wear testing for 200,000 cycles. Gravimetric measurements were performed before and after the tests to assess the weight change caused by wear. A finite element model of the implant was also developed to analyze ultrahigh-molecular-weight polyethylene (UHMWPE) damage. High localized contact pressures caused visible creep and plastic flow, deforming bushings and creating unintended UHMWPE-on-UHMWPE contact surfaces where considerably high wear rates were observed. Average experimentally measured vs. model-predicted wear was 9.5 ± 1.0 vs. 14.1 mg for the of the medial bushing, 8.5 ± 1.0 vs. 13.9 mg for the lateral humeral bushing, and 34.1 ± 0.7 vs. 36.9 mg for the ulnar bushings, respectively. Model predicted contact stresses on the surfaces of bushings were substantially higher than the yield limit of conventional UHMWPE (87 MPa for the humeral bushings and 83 MPa for the ulnar bushing). Our study discovered that unintended wear at UHMWPE-UHMWPE contact surfaces, "fed" by excessive plastic flow may, in fact, be of more concern than wear that occurs at the intended metal-UHMWPE contact interfaces. Furthermore, formation of high localized contact stresses much above the yield limit of UHMWPE is another likely contributor to bushing failure for this implant.

The performance and stability of three-lobe journal bearing textured with micro protrusions

The present research work deals with studying the steady state performance and dynamic stability of sliding element hydrodynamic bearings of the three-lobe type and provided with a bushing surface textured with uniform micro protrusions. A mathematical model has been put forward for the problem using the Reynolds equation governing the unstable fluid lubrication inside the bearing as well as the equations governing the dynamic movement of the journal. The equations have been put in their numerical forms suitable for computer solution using the finite difference method. Two types of three lobe bearings have been considered, one with its plain bushing and the other with bushing textured with uniform micro protrusions. This is in addition to other two plain journal bearings one with plain bushing and the other with textured bushing. This is for the purpose of carrying out a general comparison to include the steady performance of these bearings in terms of their load carrying capacity and the friction losses in their parts in addition to their dynamic stability. It was concluded in the present work that the inclusion of these textured micro protrusions in the bushing of bearings, whether they are plain or of the three-lobe geometry improves their performance in terms of reducing their friction losses and raising their load carrying capacity along. It was found that the three-lobe bearing with protruded bushing surface texture is superior to the other types of bearings considered in the present work as far as steady state performance is concerned. Regarding the margin of stability to small sinusoidal disturbances the protruded three-lobe bearing shows a relatively lower margin. Some useful recommendations for future research work in this field of study are given in this work and the most important one is to carry out extensive experimental studies on sliding bearings surfaces fitted with textured bushings of different micro protrusions designs.

Characteristics of Land–Air Exchange Parameters over Grassland in Southeast Tibet

Abstract Accurate parameters that describe land–air exchange processes are essential for studying and predicting atmospheric processes over the Tibetan Plateau. Radiation, atmospheric thermal and moisture conditions, and turbulent heat and momentum fluxes were measured in the Yarlung Zangbo River, southeast Tibet, in May–July 2013. Based on the data, land–air exchange parameters were derived over the grassland surface, including the aerodynamic roughness length z0m, thermal roughness length z0h, the excess resistance to heat transfer kB−1 (where k represents the von Kármán constant and B−1 represents the Stanton number), and momentum and heat transfer coefficients (CD and CH, respectively). The average z0m was 7.0 cm, with a standard deviation of 1.4 cm; these values are higher than those observed in the central and western plateau regions and may have been affected by the tall grass and bush surface covers that surrounded the observation site. The average kB−1 was 5.7 ± 1.8, which is higher than that in other plateau regions in the same season. The average CD during the observation period, (11.9 ± 1.6) × 10−3, is also higher than that of other plateau regions. The commonly used iterative scheme and three noniterative turbulent flux parameterization schemes were evaluated over southeast Tibet using the above observational data. Parameter CD was underestimated by most schemes, whereas CH was overestimated by all schemes. Additional studies suggested that the iterative scheme performed best in retrieving the land–air exchange parameters and can be applied over southeast Tibet.

Detecting Tea Bush Surface Temperature by a Thermal Imaging Method and Studying Varietal Differences and Yield Responses of the Tea Bush after Irrigation

Detecting Tea Bush Surface Temperature by a Thermal Imaging Method and Studying Varietal Differences and Yield Responses of the Tea Bush after Irrigation

Precision design of hydrostatic thrust bearing in rotary table and spindle

According to the increasing needs of rotary table and spindle to satisfy high-precision machining requirements, the accuracy of rotary table and spindle becomes an important issue due to the error averaging effect of hydrostatic thrust bearing. The objective of this study is to research a methodology to guide the precision design of hydrostatic thrust bearing in rotary table and spindle. A run-out error model based on error averaging effect is established using the Reynolds equation, pressure boundary conditions, flux continuity equations of pad and dynamic equations of shaft. The axial run-out error and angular error are calculated considering perpendicularity error and flatness error of the components. The simulation results show that the two perpendicularity errors between axis line and thrust bearing bushing surface have same direction, and the axial run-out error could reach to the maximum values. Also, the flatness error of thrust bearing bushing surface has a big influence on axial run-out error. Following the outcomes, the precision design of hydrostatic thrust bearing was conducted. The axial run-out errors of rotary table and spindle with hydrostatic thrust bearing were experimentally studied, and the results have good coherence to the simulation data. The run-out error model is demonstrated to be an effective approach to guide the precision design of hydrostatic thrust bearing in other rotary tables and spindles.

Электромеханическая закалка рабочих поверхностей шлицевых втулок техники сельскохозяйственного назначения

Электромеханическая закалка рабочих поверхностей шлицевых втулок техники сельскохозяйственного назначения

ВИБРАЦИОННОЕ ОБОРУДОВАНИЕ ДЛЯ НАНЕСЕНИЯ МАСЛОУДЕРЖИВАЮЩИХ ЛУНОК НА ШЕЙКАХ ВАЛОВ

One of the main issues of modern manufacturing engineering is the development of actions and creation of equipment for machine durability improvement within the speed range and hard loading operational modes. For today, the task of provision of the parts bulk strength under the ordinary working conditions is considered to be nearly resolved. That is why the surface layer state, its wear resistance and lubricating conditions are of great importance now. The task of improvement of oil-retaining property of sliding surfaces is essential for machines of various purposes. The paper presents the results of analysis of existing equipment for oil-retaining profiles applying and determines its weak points. The authors offered new design of vibration equipment referred to the technology of applying of oil-retaining holes on the sliding surfaces in order to decrease the friction forces and the wear of inner surface of friction bearing bush, and can be used in various branches of machine-building complex. The authors developed experimental equipment, measuring equipment and the research technique. To carry out comparative study the samples of friction couples were created. The authors carried out the study of working capacity of friction units without holes and with holes on the stub shafts using the method of assessment of size of inner bush surface wear scar. Proposed design of vibration equipment for applying of oil-retaining holes on the stub shafts allows increasing flow rate and, consequently, the metal balls impact force due to the use of inverted valve. The increase of vibration frequency will make it possible to increase the efficiency of the process of oil-retaining profile applying. The study proved the working capacity of suggested equipment and showed the decrease of friction couple wear.

Application of unusual techniques for characterizing ageing on polymeric electrical insulation

The degradation process caused by electrical stresses and weather conditions on electrical non-ceramic insulation was analyzed with non-destructive techniques. Traditional replica technique was introduced as a novel method to characterize microstructure changes on polymeric insulation. Static contact angle and roughness measurements were also used to characterize non-ceramic insulation. These non-conventional techniques have shown to be appropriate for evaluating aging on electrical insulation surfaces of bushings and surge arresters installed in electrical substations. The replica technique has drawn attention for being an innovative analysis test for characterizing polymeric insulation.

Electric stress grading on bushings of combined instrument transformers using high permittivity polymeric composites

Bushings are used in high voltage equipment to bring the high voltage conductors through a grounded structure. Due to the high electric field around the area next to the grounded structure it is required to keep the intensity of the field as low as possible in order to avoid surface discharges. In this paper, it is discussed how high permittivity composites prepared with doped and functionalized barium titanate powder can be used to control the electric stress on the surface of a polymeric bushing which is used in a combined instrument transformer with two central conductors, one at high voltage and the other at ground potential. First, it is described how the properties of the filler were improved and then it is shown how the prepared polymer/ceramic composite can modify the voltage profile along the surface of a prepared sample. By using three dimensional finite element simulations the performance of the composite bushing is compared with the stress grading obtained in a ceramic bushing with capacitive grading. According to the results, by using composite materials of increased permittivity, the electric stress on the surface of the bushing can be reduced to acceptable values without need of conductive foils.

Modeling Present Worth of Product Quality Loss of STB Characteristic Based on Service Life Distribution

The product smaller-the-better (STB) quality characteristics are continually changing and out of specification limits because of the constant stress, wear and others after the product is put into use, which will cause loss because of the product rejected and scrapped. On the basis of the quality viewpoint that product quality loss is present worth of a loss caused as a result of its quality characteristics because its quality characteristic is out of specification and lead to product scrap after the product is put into service, the paper establishes the present worth model of quality loss of STB characteristic based on service life distribution, and proposes the calculation method on the probability density function (PDF) of the product service life based on the technical specifications of STB quality characteristic. It takes the concentricity between the inner cylindrical surface and the outer cylindrical surface of the link bushing as an example to analysis the various factors that impact on the present worth of concentricity quality loss in the new model, and contrast with Taguchi quality loss model. The results show that the new model describes an actual loss that a product imparts to society after the product is put into service, and can reflect the quality loss of STB characteristic in the product service process, and is more realistic than Taguchi quality loss model of STB. The new model extends tolerance design of STB characteristic from the manufacturing stage to the service stage.

Three-Dimensional Modeling of Opposed Biconical Cone Screw High-Pressure Seawater Hydraulic Pump

The rotor and stator were major components of the opposed biconinal cone screw high pressure seawater hydraulic pump, which precision of design and manufacture was particularly high, and the combining status between the stator and rotor has a significant impact on the performance of the new type pump, so the related research on above problems are carried out. In order to satisfy the demands of design efficiency and manufacture decision, a fast and simple way was presented to model 3D cone screw and bushing. Three-dimensional space Cartesian coordinates of cone screw and bushing profile with MATLAB programming were obtained according to the cone screw and bushing surface equation and the design parameters,3D curves of cone screw and bushing with MATLAB were rendered, and the feature point space coordinates were imported to Pro/Engineer so as to build cone screw and bushing solid model. Finally, making virtual assembly and checking interference on the screw and the bushing were necessary. The proposed method can make the complex 3D modeling more accurate, feasible and efficient.

Wear and Transmission Error between PEEK Bush and 7075 Aluminium Alloy Cam Plate Components in Robot Joints

In this work, wear of reinforced poly-ether-ether-ketone (PEEK containing PTFE, graphite and carbon fibres) polymer bushes in friction against 7075 aluminium alloy cam plates is investigated in order to establish the application possibilities in transmission parts in humanoid robot joints. The PEEK bush surface conditions as well as the input axis-output axis transmission error (backlash) require close examination. Sliding wear tests were performed on bushes under 900 kgfcm loaded torque, while the cam plate oscillated. Based on the wear observation, it was found that PEEK wear fragments in the interface between PEEK bush and aluminium alloy cam plate formed a PEEK film.