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Auswahl der wissenschaftlichen Literatur zum Thema „Rotary table bearings“
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Zeitschriftenartikel zum Thema "Rotary table bearings"
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Lee, Hyun Bok, Ji Han Oh, Chang Hwan Oh und Young Hyu Choi. „Structural Design Optimization of the Rotary Table of a Floor Type Boring Machine for Minimum Weight and Compliance by Using GA“. Applied Mechanics and Materials 271-272 (Dezember 2012): 1421–26. http://dx.doi.org/10.4028/www.scientific.net/amm.271-272.1421.
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Recently needs of extra-large floor type boring machines have been increased according to super-sizing ships and aircrafts including wind turbines. The rotary table of a supersize floor type boring machine to be developed in this study can support ultra heavyweight workpieces more than 200 tons and be rotated with a speed of 300 deg/min. Therefore, it is designed as a high rigidity structure and requires high rigidity bearings. Thus, hydrostatic bearings are used in this rotary table. For optimizing the rotary table of a floor type boring machine as a lightweight and high rigidity structure, an optimized design is performed using an FEM structural analysis and a genetic algorithm (GA). As a result, it represents a decrease in weight 22.2% and an increases in rigidity 8.56% compared to that of the conventional method based on empirical design.
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Wu, Yangong, Zheng Qiao, Jiadai Xue, Yutao Liu und Bo Wang. „Root iterative method for static performance analysis of aerostatic thrust bearings with multiple pocketed orifice-type restrictors based on ANSYS“. Industrial Lubrication and Tribology 72, Nr. 1 (23.09.2019): 165–71. http://dx.doi.org/10.1108/ilt-11-2018-0429.
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Purpose The purpose of this paper is to present a novel numerical approach to analyze the static performance of aerostatic thrust bearings by adopting a general finite element method calculation program. Design/methodology/approach The characteristics of a gas film are described by the Reynolds equation and the pressure distribution is solved using the finite element method. A root iterative method is proposed to meet the requirement of the mass-conservation law because multiple pocketed orifice-type restrictors are treated as a series of special boundary conditions. Findings The static performance of a rotary table using aerostatic thrust bearings, including load carrying capacity and stiffness, can be predicted by the method; moreover, it can be further confirmed through experiments on the designed rotary table. Originality/value The method combining the finite element and root iterative methods is highly accurate and has a low time-cost for analyzing aerostatic thrust bearings with multiple pocketed orifice-type restrictors.
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Sun, Ya Zhou, Jiu Da Wu, Jing He Zhang und Hai Tao Liu. „Structure Scheme Design of a Large Ultra-Precision Hydrostatic Rotary Table with a High Diameter-Length Ratio“. Key Engineering Materials 579-580 (September 2013): 353–56. http://dx.doi.org/10.4028/www.scientific.net/kem.579-580.353.
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This essay briefly introduces a structure scheme design of a high diameter-length ratio rotary plate. This structure scheme is unique from any well-known schemes. In this scheme, there is only one flat act as the working flat for both main thrust bearing and aux thrust bearing. It minimizes the faces which need lapping. At the same time, this scheme minimizes the number of assembling parts. So, it will be easier for this scheme to achieve high accuracy. This essay includes the process of design: calculation for bearings and schemes compare.
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Jiang, Shuyun, und Chundong Xu. „Dynamics characteristics of a rotary table motorized spindle with externally pressurized air bearings“. Journal of Vibroengineering 19, Nr. 2 (31.03.2017): 801–11. http://dx.doi.org/10.21595/jve.2016.17266.
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5
Zha, Jun, Yaolong Chen und Penghai Zhang. „Precision design of hydrostatic thrust bearing in rotary table and spindle“. Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 232, Nr. 11 (26.12.2016): 2044–53. http://dx.doi.org/10.1177/0954405416682279.
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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.
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Wang, Fu Sheng, und Gang Bao. „Research on a New Type of Center of Mass Measuring Instruments“. Applied Mechanics and Materials 29-32 (August 2010): 1722–27. http://dx.doi.org/10.4028/www.scientific.net/amm.29-32.1722.
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The accurate measurement and control of center of mass (CM) in mass properties for satellite attitude control are the most important. In order to accurately measure CM, this paper describes a new type of CM measuring instruments which are particularly recommended for determining mass properties of rockets, satellite and ballistic objects. A spherical air-bearing supports a precision rotary table and acts as a frictionless pivot axis for measuring unbalance moments due to the displacement of the test part CM relative to the central axis of the bearing. This paper emphasizes the research on reasons and laws of the load table CM offset caused by the elastic deformation, and according to curve theory of thin plates derives the formulary for the element center of mass displacement of the finite element and for the platform structure center of mass elastic displacement, and calculates the CM elasticity offset and the unbalance moment caused by the deformation of loaded table. The research results provide bases for the structure design of rotary tables.
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Okahata, Go, Akinori Yui, Takayuki Kitajima, Shigeki Okuyama, Hirotsugu Saito und Alexander Henry Slocum. „Development of Rotary Work Table with Constant-Flow Hydrostatic Water Bearing for Large Scale Silicon-Wafer Grinding Machine“. Advanced Materials Research 1017 (September 2014): 604–9. http://dx.doi.org/10.4028/www.scientific.net/amr.1017.604.
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There is a compelling need for development of a surface grinding machine for 450mm diameter silicon-wafers. The authors have developed a new surface grinding machine for the large scale silicon-wafers. The machine has a rotary work table equipped with a constant-flow hydrostatic water bearing. The table system has to attain high static stiffness to achieve higher loop stiffness. This paper investigates static performances of the rotary table by numerical computation. The obtained results are compared with the experimental ones. Accordingly, it is verified that the developed rotary table has sufficient static performances for the large scale silicon-wafer grinding machine.
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Liu, Ping, und Hui Yi Miao. „Research on a Computerized Form and Position Error Measurement Instrument“. Applied Mechanics and Materials 201-202 (Oktober 2012): 151–56. http://dx.doi.org/10.4028/www.scientific.net/amm.201-202.151.
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A model machine of multifunctional form and position measurement instrument controlled by a personal computer has been successfully developed. The instrument is designed in rotary table type with a high precision air bearing and the radial rotation error of the rotary table is 0.08 μm. A high precision vertical sliding carriage supported by an air bearing is used to the instrument, the straight motion error of the carriage is 0.3 μm/200 mm and the parallelism error of the motion of the carriage relative to the rotation axis of the rotary table is 0.4 μm/200 mm. The mathematical models have been established for assessing planar and spatial straightness, flatness, roundness, cylindricity, and coaxality errors. By radial deviation measurement, the instrument can accurately measure form and position errors of such workpieces as shafts, round plates and sleeves of medium or small dimensions with the tolerance grades mostly used in industry.
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Dong, Xiang Min, Li Gang Cai, Yong Sheng Zhao und Xiao Shi. „Deformation Analysis for Hydrostatic Rotary Table of Heavy Duty CNC Machine Tool“. Applied Mechanics and Materials 457-458 (Oktober 2013): 335–39. http://dx.doi.org/10.4028/www.scientific.net/amm.457-458.335.
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The deformation of constant flow and closed type hydrostatic rotary table of heavy duty CNC machine tool has a great influence on the film thickness because of its large diameter, high load-bearing. According to the circular plate deformation theory of elasticity, differential equations of worktable deformation are derived in the simply supported conditions when bearing uniform force of different locations. Displacement curves of worktable are obtained. Force and deformation weaknesses of hydrostatic rotary table are found, which can provide theory basis for supporting location of heavy workpiece machining and whether oil film is failure or not.
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Hassan, Shaker S., Ahmed Adnan Shandookh und Omar Alaa Ihsan. „Study the Effect of Using Different Bearing Types on the Performance of Evaporative Cooler“. Al-Nahrain Journal for Engineering Sciences 21, Nr. 4 (21.12.2018): 532–38. http://dx.doi.org/10.29194/njes.21040532.
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An investigation of performance response of two types of bearings such as Cylindrical Roller Bearing and bush bearing on evaporative cooler driven by DC motor of 1500 r.p.m, through studying many parameters like vibration response, temperature raise, humidity, sound level and total performance. high quality 3D positions X, Y and Z, vibration sensors type (ADXL335 accelerometers) with Arduino mega 2560 that interfaced with Lab-View program were used to measure changes in vibration amplitude and frequency. Two temperature sensors of type (LM35) were used to investigate the temperature raise in the bearings also with Arduino mega 2560 that interfaced with Lab-View program. For humidity a sensor of type DHT22 was used, also, a portable device was used to measure electricity consumption, rotary speed and sound level in the bearings of evaporative cooler. By replacing bearings all the parameters above wear measured then a comparison between them were made to find the best performance and operation of these bearings. The obtained results from the experimental work have clarified and explained by tables and figures. It has been found that the vibration of evaporative cooler in X, Y and Z-directions increased by using two cylindrical roller bearings than using two of bush bearings. The temperature of cylindrical roller bearings increased When running the evaporative cooler more than bush bearings. the noise of Evaporative Cooler by using both types of Bearings was almost same but with a little Reduce by using cylindrical roller Bearings. Which means the Evaporative Cooler has better Performance by using bush bearings than using cylindrical roller bearings.
Dissertationen zum Thema "Rotary table bearings"
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Bezděk, Petr. „Konstrukční návrh otočného stolu s nosností 65 000 kilogramů“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-443716.
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The diploma thesis deals with the design of a rotary table for machining large non-rotary workpieces up to a maximum weight of 65 000 kg. The aim of the work is to analyze and evaluate the current state of knowledge in the field of rotary tables, to create a table design according to the assignment and its 3D model with part of the drawing documentation. The theoretical part of the work searches for solutions used in the construction of rotary tables in the category of table according to the assignment. The information obtained is further used in the design of rotary table solution variants. By evaluating the weight of the required properties and their degree of fulfillment, a variant of the design solution of the table is selected, which is then designed. The individual design steps are described and explained in the text part of the work accompanied by pictures and calculations. The result of the process is a structural design of the mechanical part of the rotary table with a 3D model and partially processed drawing documentation. The contribution of the work is the summarization of relevant information for the design of rotary tables, the processed procedure of solving the design of the table and the modeled design of the rotary table. These outputs can be further treated as documentation for the production of the designed table, the development of the rotary table design to deeper details or technical development in this area.
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Balák, Pavel. „Konstrukce otočného lineárně přesuvného stolu s pevnou boční upínací deskou pro stroj FGU RT“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230818.
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The aim of this diploma thesis is design of rotary-linear table with side clamping plate. Rotary-linear table is applicated to the profiled guideways used linear table. The work is focused on the design of the individuals nodes and their calculations.
Konferenzberichte zum Thema "Rotary table bearings"
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Jia, Q., J. Zha, C. X. Zhang und Y. L. Chen. „Precision Prediction Model and Experimental Verification of Hydrostatic Bearing-Rotor System of Ultra-Precision Machine Tools“. In ASME 2015 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/detc2015-46588.
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Error averaging effect of the pressured oil film allows for a high motion precision in hydrostatic bearings. This has many applications to ultra-precision machine tools rotor-bearing system. This paper mainly focuses on the studying factors affecting the rotor-bearing system error for hydrostatic rotation table and hydrostatic spindle in ultra-precision grinding machine. Radial run-out error was selected as precision evaluation index. A precision prediction model was established, which takes into structural and dynamic parameters of hydrostatic radial bearing rotor-bearing system into consideration. Effect of assembly tolerance, structural parameters and working conditions on the accuracy of the rotor-bearing system were analyzed. Precision measurements for the ultra-precision hydrostatic rotary table and spindle were carried out. Prediction errors of radial run-out error was found to be less than 23.5%. The model proposed in this paper has high prediction precision and can be used to guide the precision design and optimization of the ultra-precision machine tools rotor-bearing system.
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Hawkins, Lawrence A. „Shock Analysis for a Homopolar, Permanent Magnet Bias Magnetic Bearing System“. In ASME 1997 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/97-gt-230.
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A transient, nonlinear analysis was developed and used to study the effect of shock machine testing on a gas turbine simulator supported by homopolar, permanent magnet bias magnetic bearings. The magnetic bearing nonlinearities modeled included saturation effects, clearance effects, and integrator and current limits. Free vertical travel of the shock machine anvil table supporting the simulator was also modeled. The magnetic bearing model was coupled to characteristic matrix based models of the rotor and support system and integrated to produce a time simulation of system performance. The results indicate saturation of the magnetic bearing for brief periods following impacts significant enough to exceed design load capacity, followed by recovery to stable operation in less than a second. The analysis was used to evaluate sizing for the magnetic bearing and backup bearing systems and to evaluate the control system strategy.
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Nataraj, C., und Steven Marx. „Optimal Control of a Nonlinear Magnetic Bearing System Using the Trigonometric Collocation Method“. In ASME 2008 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. ASMEDC, 2008. http://dx.doi.org/10.1115/smasis2008-600.
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Magnetic bearings are non-contacting, with the rotor being suspended between electromagnets, and therefore they can eliminate the need for lube oil and reduce machinery wear. The magnetic bearing is naturally unstable, and very nonlinear. This paper proposes a method designed to suppress the motion of a nonlinear magnetic bearing system rotor due to base excitation. The method combines PD feedback with feedforward optimal control, where a measured base motion is used to select a control signal designed to suppress the rotor response. The signal is generated from a combination of subharmonic frequencies and optimized coefficients stored in a lookup table. The trigonometric collocation method (TCM) is used to generate solutions for the four degree-of-freedom system made up of a shaft suspended at each end by a magnetic bearing. The TCM method uses a trigonometric series to simulate the multiharmonic behavior of each degree-of-freedom of strongly nonlinear systems. The method is easy to use and its advantage over numerical methods is that it demands less computation, particularly with higher numbers of degrees-of-freedom.
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Ryu, Keun, und Luis San Andrés. „On the Failure of a Gas Foil Bearing: High Temperature Operation Without Cooling Flow“. In ASME Turbo Expo 2013: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-94244.
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Implementing gas foil bearings (GFBs) in micro gas turbine engines is a proven approach to improve system efficiency and reliability. Adequate thermal management for operation at high temperatures, such as in a gas turbine or a turbocharger, is important to control thermal growth of components and to remove efficiently mechanical energy from the rotor mainly. The paper presents a test rotor supported on GFBs operating with a heated shaft and reports components temperatures and shaft motions at an operating speed of 37 krpm. An electric cartridge heater loosely inserted in the hollow rotor warms the test system. Thermocouples and non-contact infrared thermometers record temperatures on the bearing sleeve and rotor OD, respectively. No forced cooling air flow streams were supplied to the bearings and rotor, in spite of the high temperature induced by the heater on the shaft outer surface. With the rotor spinning, the tests consisted in heating the rotor to a set temperature, recording the system component temperatures until reaching thermal equilibrium in ∼60 minutes, and stepping the heater set temperature by 200 °C. The experiments proceeded without incident, the heater set temperature equaled 600 °C and 10 minutes into the test, noise became apparent and the rotor stopped abruptly. The unusual operating condition, without cooling flow and a too large increment in rotor temperature, reaching 250 °C, led to the incident which destroyed one of the foil bearings. Post-test inspection evidenced seizure of the hottest bearing (closest to the heater) with melting of the top foil at the locations where it rests on the underspring crests (bumps). Analysis reveals a notable reduction in bearing clearance as the rotor temperature increases until seizure occurs. Upon contact between the rotor and top foil, dry-friction quickly generated vast amounts of energy that melted the protective coating and metal top foil. Rather than a reliability issue with the foil bearings the experimental results show poor operating procedure and ignorance on the system behavior (predictions). A cautionary tale and a lesson in humility follow.
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Kim, Tae Ho, Moon Sung Park, Jongsung Lee, Young Min Kim, Kyoung-Ku Ha, Jeonghee Park, Changha Lee und Chimyung Kim. „Identification of Dynamic Characteristics of Gas Foil Thrust Bearings Using Base Excitation“. In ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-56282.
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Gas foil bearings (GFBs) have clear advantages over oil-lubricated and rolling element bearings, by virtue of low power loss, oil-free operation in compact units, and rotordynamic stability at high speeds. However, because of the inherent low gas viscosity, GFBs have lower load capacity than the other bearings. In particular, accurate measurement of load capacity and dynamic characteristics of gas foil thrust bearings (GFTBs) is utmost important to widening their applications to high performance turbomachinery. In this study, a series of excitation tests were performed on a small oil-free turbomachinery with base excitations in the rotor axial direction to measure the dynamic load characteristics of a pair of six-pad, bump-type GFTBs, which support the thrust collar. An electromagnetic shaker provided dynamic sine sweep loads to the test bench (shaking table), which held rigidly the turbomachinery test rig for increasing excitation frequency from 10 Hz to 200 Hz. The magnitude of the shaker dynamic load, represented as an acceleration measured on the test rig, was increased up to 9 G (gravity). An eddy current sensor installed on the test rig housing measured the axial displacement (or vibrational amplitude) of the rotor thrust collar during the excitation tests. The axial acceleration of the rotor relative to the test rig was calculated using the measured displacement. A single degree-of-freedom base excitation model identified the frequency-dependent dynamic load capacity, stiffness, damping, and loss factor of the test GFTB for increasing shaker dynamic loads and increasing bearing clearances. The test results show that, for a constant shaker force and the test GFTB with a clearance of 155 μm, an increasing excitation frequency increases the dynamic load carried by the test GFTB, i.e., bearing reaction force, until a certain value of the frequency where it jumps down suddenly because of the influence from Duffing’s vibrations of the rotor. The bearing stiffness increases and the damping decreases dramatically as the excitation frequency increases. Generally, the bearing loss factor ranges from 0.5 to 1.5 independent of the frequency. As the shaker force increases, the bearing dynamic load, stiffness, damping, and loss factor increase depending on the excitation frequency. Interestingly, the agreements between the measured GFTB dynamic load versus the thrust runner displacement, the measured GFTB static load versus the structural deflection, and the predicted static load versus the thrust runner displacement are remarkable. Further tests with increasing GFTB clearances of 155, 180, 205, and 225 μm revealed that the vibrational amplitude increases and the jump-down frequency decreases with increasing clearances. The bearing load increases, but the bearing stiffness, damping, and loss factor decrease slightly as the clearance increases. The test results after a modification of the GFTB by rotating one side bearing plate by 30° relative to the other side bearing plate revealed insignificant changes in the dynamic characteristics. The present dynamic performance measurements provide a useful database of GFTBs for use in microturbomachinery.
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Branagan, L. A., und S. H. Hesler. „Fundamentals of a Babbitted Bearing Repair Assistant“. In ASME 2016 Power Conference collocated with the ASME 2016 10th International Conference on Energy Sustainability and the ASME 2016 14th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/power2016-59389.
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Fluid film bearings provide critical support for the rotors in gas turbines, steam turbines, generators, exciters and other machines through the generation and support of a hydrodynamic film. Industrial bearings are lined with a babbitt material which serves as a sacrificial element during operation and may need to be refurbished depending on the past operating and maintenance history. After inspection, engineering judgment is typically used during a machine overhaul to determine whether a bearing requires refurbishment. This engineering judgment is developed through an understanding of the principals of bearing design, machine operation, machine monitoring and babbitt wear / damage characteristics. This paper describes the criteria to serve as a basis for a decision support tool relative to the refurbishment of a babbitted, fluid-film bearing. Those criteria start with key descriptors of any damage to the bearing and evaluate the remaining load capacity, repairability, bearing support, rotordynamics influence, journal conditions and pivot conditions. The descriptors focus on visual examinations of the condition of the babbitt and seek to be intuitive, yet remaining comprehensive; to this end a graphical interface is used where feasible. Evaluations include specific load capacity calculations, determination of damage factors for the principal modes of babbitt damage and data from lookup tables whose input is based on experience. These evaluations are combined to provide the basis for the refurbishment decision. Scaling efforts are incorporated into the evaluations to allow their combination into a single bearing condition index. Initial experience suggests that discrete ranges of the bearing condition index are preferable to numerical value. One goal of the tool is to allow use by inexperienced engineers as a support to their technical development. Another goal is to better document the decision process for particular bearings. The preliminary tool was applied to a cylindrical, radial bearing in a horizontal orientation and to a bumper thrust bearing. Initial results have confirmed the general strategy employed and have suggested areas requiring refinement.
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Sugimura, Nobuhiro, Hitomi Watabiki, Wiroj Thasana, Koji Iwamura und Yoshitaka Tanimizu. „Analysis of Kinematic Motion Deviations of Rotary Tables Based on Geometric Tolerances“. In ASME/ISCIE 2012 International Symposium on Flexible Automation. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/isfa2012-7113.
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Machine tools are recognized as key components of manufacturing systems, and product quality and cost mainly depend on performances of the machine tools. Much progress has been made in the machine tool technologies, aimed at improving the performances of the machine tools from various viewpoints, such as accuracy, reliability, productivity, and flexibility. The machining accuracy is one of the most important characteristics of the machine tools. From the viewpoints of the design and the manufacturing of the machine tools and their components, one of the important issues is to clarify the relationships between the kinematic motion deviations of the machine tools and the geometric tolerances of the components, such as the guide ways and the bearings. The objective of the present research is to establish mathematical models representing the kinematic motion deviations of the machine tools, on the basis of the geometric tolerances of the components, and to apply the models to theoretical analysis of the kinematic motion deviations of the machine tool components.
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Vetter, Daniel, Thomas Hagemann und Hubert Schwarze. „Potentials and Limitations of an Extended Approximation Method for Nonlinear Dynamic Journal and Thrust Bearing Forces“. In ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-75662.
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Nonlinear dynamic journal bearing modeling within rotordynamic analyses requires the calculation of the nonlinear bearing forces particularly depending on shaft eccentricity and velocity. The bearing forces can be calculated properly using Reynolds differential equation and mass conserving cavitation algorithms, based for example on Elrod’s cavitation algorithm. This approach achieves high model accuracy and allows the consideration of additional effects like misalignment, variable viscosity and transient local oil distribution in the lubricant film. However, despite rising calculating capacity dynamic bearing analyses are still very CPU-time consuming and, consequently, approximation methods are commonly applied in multibody or rotordynamic analyses, especially in day-to-day business. While many approximation procedures are limited to special bearing geometries Glienicke et al. describe a method which is flexible to model different journal bearing geometries, as well as to consider many additional effects like oil supply pressure or starved lubrication conditions in a time averaged manner. It can be applied for both fixed-pad and tilting-pad journal bearings and its characteristic data is included in an a priori calculated map enabling a time-efficient call up of characteristic parameters of the bearing forces from a look-up table in dynamic simulations. Further, the data can be transferred to any other bearing if the requirements of the theory of similarity are supposed to be valid. In this investigation, the method is first successfully extended by the authors to consider misalignment. Secondly, the general idea of the procedure is transferred and applied to thrust bearings in order to enable a six degree of freedom rotordynamic modeling. In case of a simply lateral movement and rotation-symmetric bearing design the procedure is simple, though, in case of tilting movements it becomes more complicated. A misaligned thrust bearing provides tilting and cross-coupling moments. Cross coupling moments are smaller than the main moments, but have similar orders of magnitude and should therefore be considered. Strategies are investigated for a proper approximation of the nonlinear thrust bearing main and cross-coupling forces and moments. All steps are verified using a direct solution of Reynolds differential equation based on an extended mass conserving algorithm adapted from Elrod’s numerical implementation for the stationary case. Finally, the whole procedure and its application to rotordynamic analysis is verified by comparisons with results gained using direct online solution of Reynolds equation in rotordynamic simulation. While good simulation quality of this approximation approach is documented for selected rotor-bearing-systems in literature the range of validity is not clearly defined. Here, the influences of different parameters on the simulation error are investigated conducting different variation calculations for an overhung rotor with documented vibrational behavior from literature. It is shown that the simulation quality depends on the cavitation zone and decreases with rising vibrational velocity. The root cause for this upcoming error and a possible modification for the elimination of this limitation are presented.
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Shan, Xiaobiao, Jiangbo Yuan, Tao Xie und Haiqun Qi. „A new approach for determining the contact indentation of the wire race ball bearing in a three-axis simulating rotary table“. In 2009 International Conference on Mechatronics and Automation (ICMA). IEEE, 2009. http://dx.doi.org/10.1109/icma.2009.5244884.
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Alexandre, Armando, Raffaello Antonutti, Theo Gentils, Laurent Mutricy und Pierre Weyne. „Simplified Aerodynamic Loading Model for Non-Production Conditions for Floating Wind Systems Design“. In ASME 2021 3rd International Offshore Wind Technical Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/iowtc2021-3516.
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Abstract Floating wind is now entering a commercial-stage, and there are a significant number of commercial projects in countries like France, Japan, UK and Portugal. A floating wind project is complex and has many interdependencies and interfaces. During all stages of the project several participants are expected to use a numerical model of the whole system and not only the part the participant has to design. Examples of this are the mooring and floater designer requiring a coupled model of the whole system including also the wind turbine, the operations team requiring a model of the system to plan towing and operations. All these stakeholders require a coupled model where the hydrodynamics, aerodynamics and structural physics of the system are captured with different levels of accuracy. In this paper, we will concentrate on a simplified model for the aerodynamic loading of the turbine in idling and standstill conditions that can be easily implemented in a simulation tool used for floater, mooring and marine operations studies. The method consists of using a subset of simulations at constant wind speed (ideally close to the wind speed required for the simulations) run on a detailed turbine model on a rigid tower and fixed foundation — normally run by the turbine designer. A proxy to the aerodynamic loads on the rotor and nacelle (RNA) is to take the horizontal yaw bearing loads. The process is then repeated for a range of nacelle yaw misalignments (for example every 15° for 360°). A look-up table with the horizontal yaw bearing load for the range of wind-rotor misalignments investigated is created. The simplified model of the aerodynamic loads on the RNA consists of a fixed blade (or wing) segment located at the hub, where aerodynamic drag and lift coefficients can be specified. Using the look-up tables created using the detailed turbine model, drag and lift coefficients are estimated as a function of the angle between the rotor and the wind direction. This representation of the aerodynamic loading on the RNA was then verified against full-field turbulent wind simulations in fixed and floating conditions using a multi-megawatt commercial turbine. The results for the parameters concerning the floater, mooring and marine operations design were monitored (e.g. tower bottom loads, offsets, pitch, mooring tensions) for extreme conditions and the errors introduced by this simplified rotor are generally lower than 4%. This illustrates that this simplified representation of the turbine can be used by the various parties of the project during the early stages of the design, particularly when knowing the loading within the RNA and on higher sections of the tower is not important.
Berichte der Organisationen zum Thema "Rotary table bearings"
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Accatino, Mark R. Design, development and evaluation of a precision air bearing rotary table with large diameter through-hole. Office of Scientific and Technical Information (OSTI), November 1991. http://dx.doi.org/10.2172/10178466.
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