Showing papers on "Fluid bearing published in 1987"

Modelling Flow in an Intermeshing Co-rotating Twin Screw Extruder: Flow in Kneading Discs

Abstract: A model for simulation of flow in an intermeshing kneading disc region of corotating twin screw extruder is presented. This is based on hydrodynamic lubrication theory for a Newtonian fluid. Numerical procedures are used to compute the pressure distribution and flow field in the kneading disc region. The influence of staggering angle, nip clearance, screw speed and throughput rate are investigated.

Resiliently mounted fluid bearing assembly

Abstract: A fluid bearing assembly, e.g., air or gas, of the hydrostatic or hydrodynamic type, for use as a spindle and the like, includes spaced journals mounted on a shaft for rotation therewith. The housing includes spaced support bearings cooperating with the journals to form a gas gap therebetween. The support bearings are resiliently mounted in the housing for axial, radial and angular movement through the use of continuous resilient support elements positioned between the housing and the support bearings and continuously in contact with each. The resilient support elements are preferably self-energizing and comprised of relatively low coefficient of friction materials to reduce the friction of the system thus allowing rapid adjustment of the bearing in response to loads on the shaft. Various details are described with respect to the various structures illustrated, including the details of an air bearing spindle assembly of relatively light weight and capable of operating at speeds in excess of 100,000 RPM.

Reduction of friction between a tape and a smooth surface by acoustic excitation

Abstract: The frictional force acting on a tape moving in contact with a smooth surface leads to wear of the latter. An important example exists where the magnetic tape is wrapped around or supported on surfaces that do not have hydrostatic air bearings or hydrodynamic air bearings during start/stop in a tape‐drive system; the abrasion of the bearing surface by the tape results in the generation of debris and wear. This communication describes our observation that the friction between a magnetic tape and a smooth glass surface can be significantly reduced by acoustic excitation of the tape or of the glass surface. Possible explanation of the observation in terms of a squeeze film theory is discussed.

Inertia Effect in Hydrodynamic Lubrication With Film Rupture

Abstract: Effets de l'inertie dans le cas de la lubrification hydrodynamique avec rupture du film lubrifiant

Paper II(ii) Historical aspects and present development on thermal effects in hydrodynamic bearings

Abstract: Thermal effects in hydrodynamic lubrication were recognized as very important since the first works in this field. This paper presents the evolution of research concerning thermal effects in hydrodynamic bearings from the first study published by Hirn in 1854. A summary of general thermoelastohydrodynamic theory for the journal bearing case and its comparison with experimental results is then presented.

An Application of the Finite Element Method to the Thermohydrodynamic Analysis of a Thin Film Cylindrical Bore Bearing Running at High Sliding Speed

Abstract: Utilisation de la methode des elements finis pour l'analyse thermohydrodynamique d'un palier a alesage cylindrique a film mince avec de grandes vitesses de glissement

Magnetic fluid bearing device

Abstract: PURPOSE:To obtain high bearing-hardness and a superior sealing function in a simple structure for a bearing device in the caption by constructing a radial bearing provided inside the opening end side of a non-magnetic housing with a permanent magnet having a minute bearing-gap sealing magnetic fluid therein. CONSTITUTION:One end of a non-magnetic housing 23 is closed by a thrust bearing 27 and a radial bearing made of a permanent magnet 29 having a minute bearing-gap forward a rotary shaft 21 is fitted to the opening end side thereof and magnetic fluid 31 is sealed in space 30. Accordingly, high hardness and a superior sealing function are obtained in a simple structure and they can be mass-produced at a low cost.

Dynamic Characteristics of Air-lubricated Slider Bearings for Magnetic Disk Files : Calculation by Finite Element Method : Vibration, Control Engineering, Engineering for Industry

Abstract: The floating clearance between the floating head sliders and disks of large capacity magnetic disk files is getting smaller and smaller, with the present values ranging form 0.3 to 0.5 μm. To ensure reliability, dynamic characteristics of sliders subjected to disk oscillation or runout munt be accurately predicted. Finite difference methods or the divergence formulation methods have, to the present, been used to obtain dynamic characteristics of sliders, but difficulties have arisen in treating complex-shaped sliders. In this paper, the finite element method is used to solve these difficulties. The calculated results agree with those obtained by the above-mentioned conventional methods. They also agree with the experimental results obtained using a flat taper-type slider with a yaw angle. Furthermore, the dynamic characteristics of a grooved slider and a negative pressure induction slider have been predicted by this calculation method .The present method is formulated to include the calculations of both static and dynamic characteristics.

High-pressure gear pump (or motor) with combined dynamic-static pressure bearing

Abstract: The utility model belongs to the field of gear pump or motor, adopting a combining dynamic-static pressure bearing with high relief ratio designed according to the elastic hydrodynamic lubrication theory. The combing dynamic-static pressure bearing has three structural elements, a static pressure oil chamber, a restrictor, a low-pressure lubrication groove. Compared with the sliding bearings with polytetrafluoroethene steel backing composite materials extensively used both at home and abroad, the utility model has high mechanical efficiency and overall efficiency, wide speed range of high efficiency, low technological requirement and low cost, and convenient optimum design can be performed to determine the speed range of high efficiency of an oil pump in advance.

Shaft support comprising static fluid bearings

Abstract: A shaft support comprising a shaft (3) supported by a radial and an axial static fluid bearing, which shaft is rotatably arranged in a bearing sleeve (1) and is provided with a flange-shaped compensation member (31), of which a part is situated in a compensation space (51). The compensation space (51) is connected to a pressure source so that a radially acting resulting force is exerted on the compensation member (31) and the shaft (3). The shaft support is particularly suitable for use with comparatively accurate bearings having a comparatively high bearing capacity.

A Finite Element Analysis of the Navier-Stokes Equations Applied to High Speed Thin Film Lubrication

Abstract: Analyse par elements finis des equations de Navier-Stokes appliquees a un palier a film mince pour grandes vitesses

Fluid film lubrication, Osborne Reynolds centenary : proceedings of the 13th Leeds-Lyon Symposium on Tribology, held in Bodington Hall, the University of Leeds, England, 8-12 September 1986

Abstract: A selection. I. Keynote Address. Osborne Reynolds (A. Cameron). II. History. Historical aspects and present development on thermal effects in hydrodynamic bearings (M. Fillon et al.). Michell and the development of tilting pad bearings (J.E.L. Simmons, S.D. Advani). III. Journal Bearings. An approximate global thermal analysis of journal bearings (D.F. Wilcock). Negative pressures in statically and dynamically loaded journal bearings (S. Natsumeda, T. Someya). Mixing inlet temperatures in starved journal bearings (H. Heshmat, P. Gorski). Starvation effects in two high speed bearing types (D.T. Gethin, J.O. Medwell). IV. Thrust Bearings (1). Three dimensional computation of thrust bearings (C.M.McC. Ettles). Parametric study and optimization of starved thrust bearings (H. Heshmat et al.). Tilting pad thrust bearings tests: influence of three design variables (W.W. Gardner). An experimental study of sector-pad thrust bearings and evaluation of their thermal characteristics (T.G. Rajaswamy et al.). Hard-on-hard water lubricated bearings for marine applications (P.J. Lidgitt et al.). V. Thrust Bearings (2). Inlet boundary condition for submerged multi-pad bearings relative to fluid inertia forces (A. Mori, H. Mori). Pressure boundary conditions at inlet edge of turbulent thrust bearings (H. Hashimoto, S. Wada). Dynamic analysis of tilting pad thrust bearings (A. Benali et al.). Hydrodynamically lubricated plane slider bearings using elastic surfaces (C. Giannikos, R.H. Buckholz). VI. Elasto-Hydrodynamic Lubrication (1). Solving Reynolds' equation for EHL line contacts by application of a multigrid method (A.A. Lubrecht et al.). The use of multi-level adaptive techniques for EHL line contact analysis (R.J. Chittenden et al.). Solutions for isoviscous line contacts using a closed form elasticity solution (R. Hall, M.D. Savage). VII. Elastohydrodynamic Lubrication (2). Parametric study of performance in elastohydrodynamic lubricated line contacts (B.J. Hamrock et al.). A numerical solution of the elastohydrodynamic lubrication of elliptical contacts with thermal effects (A.G. Blahey, G.E. Schneider). VIII. Elastohydrodynamic Lubrication (3). The lubrication of elliptical conjunctions in the isoviscous-elastic regime with entrainment directed along either principal axis (R.J. Chittenden et al.). The elastohydrodynamic behaviour of simple liquids at low temperatures (C. Waterhouse et al.). IX. Elastohydrodynamic Lubrication (4). A method for estimating the effect of normal approach on film thickness in elastohydrodynamic line contacts (N. Motosh, W.Y. Saman). A full numerical solution for the non-steady state elastohydrodynamic problem in nominal line contacts (Y.W. Wu, S.M. Yan). The lubrication of soft contacts (C.J. Ho oke). X. Lubricant Rheology. Pressure viscosity and compressibility of di fferent mineral oils (P. Vergne, D. Berthe). Measurement of viscoelastic paramet ers in lubricants and calculation of traction curves (P. Bezot, C. Hesse-Bezot).

The Effect of Two-Phase Lubricant on Bearing Performances

Abstract: The effect of small, spherical, rigid particles, droplets or bubbles (henceforth referred to as particles) on the performance of a hydrodynamic bearing is theoretically investigated. A low Reynolds number solution for a single particle is utilized to obtain the integrated effect of a dilute suspension. Two examples are addressed: a long Rayleigh step slider and a long journal bearing. It is found that load-carrying capacity is negligibly affected by the presence of the particles, whereas the friction is increased appreciably. Presented at the 41st Annual Meeting in Toronto, Ontario, Canada May 12–15, 1986

Fatigue Damage of Gear Teeth in Speed Reducers Moving Heavy Rotors

Abstract: An analytical investigation was undertaken of the dynamic loading and fatigue of the gear teeth of turbine generator turning gear mechanisms during engagement, using a nonlinear function of speed and load for the coefficient of friction, which was determined experimentally under stick-slip conditions and considering backlash. When heavy rotors are rotating on fluid bearings at low speeds, they are sometimes subject to stick-slip. The fatigue damage resulting in such systems due to the stick-slip self-excited vibrations developed on the bearings, and the backlash of the gear teeth can be predicted by a simulation procedure described in this paper. The effects of some design parameters on the fatigue life reduction and tooth loading are also investigated so that they may be used in design.

Thrust bearing device for vertical rotor

Abstract: PURPOSE: To enhance safety of magnetic bearings by providing auxiliary thrust collars, elastic buffering plates and ball-type thrust bearings in the lower part of the magnetic thrust bearings CONSTITUTION: In the lower part of magnetic thrust bearings 5a, 5b are disposed on auxiliary thrust collar 10 and ball-type thrust bearings 11, 12 Elastic buffering plates 13, 14 are fixed onto the bearing surfaces of the ball-type thrust bearings 11, 12 Under the tension state, non-operation of the magnetic thrust bearings 5a, 5b results in the fall of a rotary shaft 1a Thereat, the lower surface of the auxiliary thrust collar 10 comes into contact with the elastic buffering plate 14 before the lower surface of a main thrust collar 8 comes into contact with the magnetic thrust bearing 5b so as to absorb shock, and further the rotary shaft 1a can be supported by the ball-type thrust bearing 12 COPYRIGHT: (C)1988,JPO&Japio

A Study of the Characteristic Analysis of High-speed Journal Bearings : Optimum Design of Journal Bearings : Vibration, Control Engineering, Engineering for Industry

Abstract: This paper describes an optimum design of hydrodynamic journal bearings under laminar and turbulent operating conditions. Simplified closed-form design formulas are presented for the eccentricity ratio, friction force on the journal surface and whirl onset velocity as a function of the Sommerfeld number or eccentricity ratio. The radial clearance, slenderness ratio and viscosity of oil, which optimize both the oil flow rate and the oil film temperature rise in hydrodynamic journal bearings under a constant load, are determined numerically for a wide range of journal revolution speeds.

Effects of Skew Unidirectional Striated Roughness on Hydrodynamic Lubrication: Part 2—Moving Roughness

Abstract: Influence de rainures paralleles inclinees par rapport au deplacement sur la lubrification hydrodynamique. Cas d'une surface rugueuse en mouvement par rapport a une surface lisse

Paper III(iii) Mixing inlet temperatures in starved journal bearings

Abstract: Cold and hot oil mixing at the inlet to a hydrodynamic bearing has been an unresolved and critical problem in determining bearing performance; this is aggravated in the case of starved bearings by the fact that the ratio of recirculating hot oil to cold supply oil is higher than in fully lubricated bearings. The paper provides an experimental investigation of the levels of inlet temperatures in journal bearings for the case of insufficient oil supply. Aside from the customary functional dependence on operating conditions, the additional parameter considered here is the degree of starvation which ranges from full lubrication to only some 10% of the required supply. A correlation is offered that provides an estimate of the expected mixing temperature in terms of known geometric and operational parameters.

Microscopic Fluctuations in Air Bearings Measured by Novel Piezoelectric Sensors

Abstract: High performance air bearing sliders for magnetic recording must reliably maintain spacings of less than an optical wavelength with respect to the disk surface To achieve higher areal density even closer spacings are desired, but then reliability concerns increase and more sensitive tools are needed to measure head-disk interactions Novel piezoelectric sensors will be described which allow simultaneous sensing of slider dynamics, impacts, and microscopic disk roughness (even less than 20 nm) The latter phenomenon was previously unobserved and has interesting consequences for air bearing design Comparisons to non-piezoelectric sensing will be given