Large-size Bearings Research Articles

Preventive maintance plan for SKF Latin Trade SAS equipment

This research presents the design and implementation of the preventive and predictive maintenance plan developed for the seven polishing machines of the Swedish multinational SKF, of the LSB (Large Size Bearing) line. Based on Reliability Centered Maintenance (RCM), which allows identifying the most relevant equipment for the process through a criticality analysis adopting strategies in order to eliminate the occurrence of failures. The methodology implemented in this research allowed the generation of maintenance tasks that facilitated the management and visualization of the information of each asset. The company provides maintenance services for large bearings used in cement plants, foundries and industrial material transport machines, seeking to optimize production methods and the application of this theoretical and analytical procedure allowed verifying that the conditioning services offered by the company are more efficient, demonstrating with figures the retribution of the plan.

Research on the Application of Manufacturing Technology for Large-size Bearing Raceway Surface Integrity

Various types of standard and non-standard large-size rolling bearings, which function as a rotating force and a main bearing force in the equipment, have continuously improved their performance requirements. This paper proposes surface integrity manufacturing technology for Large-size Bearing Raceway, analyzes the domestic and international overview and development level, research content and key technologies, and the expected indicators and social benefits.

Research on Increasing the Performance of Wind Power Plants for Sustainable Development

A topical issue globally is the development and implementation of renewable energy sources for sustainable development. To meet current requirements, the research in this paper is directed towards finding solutions to increase the performance and efficiency of wind power plants by implementing innovative solutions for hollow roller bearings developed through the use of sustainable growth programs in the field of green energy. Another solution that has the effect of increasing wind power performance consists of the implementation of a new large-size lubrication system for large-size bearings in wind energy units, which will increase their durability by developing maintenance capabilities. In this research, we will explore the possibility of introducing an innovative automated lubrication system in hollow roller bearings. The main results of the research, the innovative constructive solutions, will lead to important savings by lowering wind farm maintenance costs, increasing the durability of large bearings, and increasing the energy efficiency and yield of the whole system. The expected impact of implementing the solutions found will mainly be in the field of sustainable growth and environmental development.

Incipient fault detection of wind turbine large-size slewing bearing based on circular domain

Incipient fault detection of wind turbine large-size slewing bearings is crucial to their high availability and profitable operation. Many studies have been conducted using time-domain, frequency-domain analysis for fault feature extraction. However, they suffer from inherent disadvantages, such as spectrum leakage analysis under variable speed, which make them unsuitable for incipient fault detection. To overcome these shortcomings, a novel incipient weak fault feature extraction method is proposed based on circular domain analysis and piecewise aggregate approximation. A systematic methodology based on circular domain resampling approach is proposed to map the time series signals into angle domain, and eliminate the time attribute. Piecewise aggregate approximation with neighborhood correlation is utilized to reduce the amount of circular-domain signals, and detect the frequency variation of vibration signals when an incipient fault occurs. The application and superiority of the proposed methodology are validated using a wind turbine large-size bearing life-cycle test dataset. Meanwhile, a comparison is conducted between traditional fault features and various circular domain models. Results show that the proposed method has a better performance in detecting incipient faults for wind turbine large-size bearing.

Evaluation of Wear on Macro-Surface Textures Generated by ns Fiber Laser

The demand for improved performance and long term reliability of mechanical systems dictate the use of advanced materials and surface engineering techniques. A small change in the surface topography can lead to substantial improvements in the tribological behaviour of the contact surfaces. One way of altering the surface topography is by surface texturing by introducing dimples or channels on the surfaces. Surface texturing is already a successful technique which finds a wide area of applications ranging from heavy industries to small scale devices. This paper reports the effect of macro texture shapes generated using a nanosecond fiber laser on wear of high carbon chromium steel used in large size bearings having rolling contacts. Circular and square shaped dimples were generated on the surface to assess the effect of sliding velocities on friction coefficient. Graphite was used as solid lubricant to minimise the effect of wear on textured surfaces. The laser parameters such as power, scan speed and passes were optimised to obtain macro circular and square dimples which was characterised using a laser confocal microscope. The friction coefficients of the circular and square dimples were observed to lie in the same range due to minimum wear on the surface. On the contrary, at medium and higher sliding velocities, square dimples exhibited lower friction coefficient values compared to circular dimples. The morphology of textured specimen was characterised using Scanning Electron Microscope.

Characterization of High-Power Turbomachinery Tilting Pad Journal Bearings: First Results Obtained on a Novel Test Bench

Tilting pad journal bearings are usually employed in turbomachines for their stable behavior at high rotational speeds. Devoted test rigs have been realized to validate the predictions of theoretical models. However, the design of new high-performance and large-size bearings needs to be supported by experimental investigations on high-performance large test rigs. The main characteristics of a recently built facility for testing large tilting pad journal bearings with diameters from 150 to 300 mm are described in this work. The test rig is versatile and can be used to test bearings of different size, configurations and to investigate the influence of many parameters, even the effect of misalignment. Sample results of the static characterization of a four-pad high-performance tilting pad journal bearing are reported evidencing some transient effects. A few sample dynamic results are also reported. The presented experimental results demonstrated the capabilities of the rig for investigating the static and the dynamic characteristics of the bearings accurately measuring slow and fast variables.

Microstructural Characterization and Hardening Mechanism of Steel for Large Size Bearing Ring Under Fast Heating and Short Soaking Time Condition

AbstractThe microstructure changes of steel for large size bearing ring with different Ni contents at different cooling rates under fast heating and short soaking time condition are analyzed by using thermal simulation test, scanning electron microscope (SEM), field emission scanning electron microscope (FESEM), electron‐backscattering diffraction (EBSD), and transmission electron microscope (TEM). The hardness is evaluated by Rockwell hardness test and the hardening mechanism is discussed. Full martensite cooling rate can be lowered from 10 to 3 °C s−1 by the addition of 0.59% Ni. At full martensite cooling rate range, the martensitic lath structures are refined by adding 0.59% Ni or increasing the cooling rate. The hardness increases progressively with the cooling rate due to the refinement of martensitic lath structures and the precipitation strengthening of M23C6‐type carbides. But the grain boundary strengthening has predominance. The highest hardness values of steel No. 2 with higher Ni is 60 and 2.5 HRC higher than that of steel No. 1 at the cooling rate of 100 °C s−1. This increase of hardness in steel No. 2 can be attributed to the finer martensitic lath structures and the solid solution strengthening. The grain boundary strengthening is the main influencing factor.

Fuzzy chaos method for evaluation of nonlinearly evolutionary process of rolling bearing performance

The failure of a rolling bearing in running usually has an early sign along with a time history, in which a time series of its performance performs abnormally. There should be a mutant gene driving the time series change according to genetics point of view, but so far it has not been found, having difficulty in mathematical revealing the inherent mechanism of variation of the rolling bearing performance. For this reason, fusing the fuzzy set theory and the chaos theory, a fuzzy chaos method is proposed to evaluate the nonlinearly evolutionary process of the rolling bearing performance as a time series. The fuzzy equivalence relation based on a phase space is employed to represent the mutant gene and the optimum measure for fuzzy equivalence relation is advanced to uncover the essence of variation of the rolling bearing performance. The experimental investigation on the vibration acceleration of the small size bearing and the friction torque of the large size bearing shows that the fuzzy chaos method is correct and effective.

Research on Flexibility of Bearing Rings for Multibody Contact Dynamics of Rolling Bearings

The flexibility of bearing rings is very important to calculate the characteristics of rolling bearings in some rolling bearing applications such as planetary gear, rolling mill and aircraft. It may cause significant changes in dynamics characteristics, bearing deflections, contact stresses, and fatigue endurance, especially under heavy applied load, large size bearing, hollowed shaft and nonrigid bearing housing. The purpose in the work presented is to research a new approach and multibody model of bearing rings for MBS of mechanical system with rolling bearings. The flexibility and three-dimensional multibody model of bearing rings have been developed using equivalent rigid elements and curved Timoshenko beam elements. The simulation of the bearing rings vibration response will be presented. In addition to the presented multibody model, the FEM model and analytical model are also used to perform the vibration analyses of the bearing ring. An investigation of the actual static deformation field of the outer ring loaded by 5 balls has been carried out for the radial displacement field using the presented model. The total number of the discrete equivalent rigid elements and CTB elements has an important effect on the predicted frequencies, however the results will be minimal changes when the elements are achieved a certain number. In such situations, the presented approach can provide multibody rings model for contact dynamics of rolling bearings with acceptable accuracy and considerably less computational effort. The calculated radial static deformation is critical to load distribution, life fatigue and dynamics characteristics of rolling bearings. The three-dimensional multibody model of bearing rings developed here and the predicted frequencies agree well with the analytical results and FEM.

Superelement-Based Modeling of Load Distribution in Large-Size Slewing Bearings

The supporting structures in large-size slewing bearings are highly flexible. In order to choose the proper bearing and shape the load-carrying structure one must estimate the distribution of forces among the individual rolling elements. Advanced numerical models are needed for this. An original method of modeling the rolling element-track system is presented and its usefulness for modeling large-size bearings is demonstrated. The results of an exemplary analysis are presented in the form of graphs and figures. The superelement-based discrete bearing models are so far most comprehensive and take into account all the phenomena involved in the bearing-supporting structures system. The application of the finite-element method and the models based on the track-rolling element-track superelement made it possible to determine the effect of the deformability of the supporting structures and the nonuniformity of their flexibility on the loading of the rolling elements in the two-row bearing. The use of formulas which do not take into account the flexibility of the supporting structures to determine the distribution of the load among the rolling elements is unacceptable.

The unipolar ASR : Viable option in unsalvageable femoral head conditions in the young patient

Background: The management of unsalvageable femoral head conditions in the young patient has remained an unresolved dilemma. Articular surface replacement of the hip has recently made some headway in terms of providing near-normal hip joint mechanics and function. However, this surgery has been limited to early stages of arthritis only with reasonable maintenance of head-neck congruity and morphology. Femoral neck fractures, osteonecrosis with large segment collapse, advanced arthritis with femoral incongruity, etc are traditional contraindications to the resurfacing technique. Methods: We present here a report on our series of 20 cases of unsalvageable femoral heads in young patients (age range, 27 to 52yrs), over a twelve month period (Aug 2004 to Jul 2005), treated with the unipolar ASR prosthesis. Fifteen patients (two had bilateral hip pathology) had primary or secondary arthritis (degenerative, post-traumatic, ankylosing spondylitis and post­avascular necrosis) while three had old operated femoral neck fractures. All patients underwent hip replacement surgery using the Unipolar ASR prosthesis. Results: Clinical and radiological results at 6-month follow up have been very encouraging and warrant further study. At an average of 4 months post-operatively, patients were able to squat, sit on the ground and perform light sporting activities. Conclusions: The Unipolar ASR prosthesis is an extension of the articular resurfacing technique employing similar principles (large size bearings, metal-on-metal interfaces), and has incorporated the advantages of the uncemented technique. We propose that this technique be more frequently used so as to brighten the prognosis of the young active patient with unsalvageable hip conditions, especially in the Asian scenario.