Spherical Hydrostatic Bearings Research Articles

Carrying Capacity of Spherical Hydrostatic Bearings Including Dynamic Pressure

Carrying Capacity of Spherical Hydrostatic Bearings Including Dynamic Pressure

Carrying Capacity of Spherical Hydrostatic Bearings including Elastic Deformation

This paper presents a theoretical model for calculating the carrying capacity of spherical hydrostatic bearings, including the deduction and solution of differential equations for fluid flow in the oil seal and the generation of bearing characteristic parameters. An example is used to verify the accuracy of the proposed calculation model. Additionally, the influence of dynamic pressure on the bearing capacity is investigated under various speed conditions. The results demonstrate that as the minimum width of the oil gap decreases, the maximum dynamic pressure increases non-linearly. Furthermore, the maximum dynamic pressure increases with higher rotational speeds, particularly when the width is smaller.

Analytical study of the spherical hydrostatic bearing dynamics through a unique technique

Because of their self-alignment property and design simplicity, the spherical hydrostatic bearings have the advantage over the other bearing configurations. Their static and dynamic performances have been intensively studied. Focusing on the bearing dynamic performance, it could be realized that the researchers used to mechanically excite the bearing in the experimental studies and perturb the rotor (spatial finite displacement) in the theoretical studies, observing its behavior and expressing it by dynamic stiffness and damping coefficient. Owing to a lack of information on bearing oscillation, this study adopts a new method to analyze this bearing behavior theoretically and grasp its nature. Unusually, the bearing vibration is studied hydro-dynamically rather than mechanically, showing the effect of eccentricity, inertia, restrictor type, seat configuration, and the supply pressure on the performance. New and unique formulas have been derived to predict the frequency, stiffness, and dampness, explaining how these parameters create the bearing self-alignment property. Some thrust bearings, designed with different techniques, have been examined where the results show vibration even in the bearing’s stationary state. Also, the newly derived formulas could precisely predict the rotation and rotational speed of the Kugel ball (recently proved and designed as a spherical hydrostatic bearing).

Hydrostatic Bearing Characteristics Investigation of a Spherical Piston Pair with an Annular Orifice Damper in Spherical Pump

The spherical pump is a totally new hydraulic concept, with spherical piston and hydrostatic bearing, in order to eliminate the direct contact between the piston and cylinder cover. In this paper, the governing Reynolds equation under spherical coordinates has been solved and the hydrostatic bearing characteristics are systematically investigated. The operating sensitivities of the proposed spherical hydrostatic bearing, with respect to the piston radius, film beginning angle, film ending angle, film thickness, and temperature, are studied. The load carrying capacity, pressure drop coefficient, stiffness variation of the lubricating films, leakage properties, and leakage flow rates are comprehensively discussed. The related findings provide a fundamental basis for designing the high-efficient spherical pump under multiple operating conditions. Besides, these related results and mechanisms can also be utilized to design and improve other kinds of annular orifice damper spherical hydraulic bearing systems.

Hydrostatic supports in test and measuring equipment

The relevance and advantages of hydrostatic supports in test and measuring equipment are shown. Structural and operational features are given when using hydrostatic supports as hydrostatic guides in vibration bars, vibration systems and measuring devices, ensuring minimum friction and smooth movement. The use of spherical hydrostatic bearings in ball joints allowing to create high-frequency pulse systems is shown. Examples of application of hydrostatic bearings in actuators, drives and spindle assemblies of test and measuring equipment are given.

Design procedure of an advanced spherical hydrostatic bearing used in rotary forging presses

In this paper, the principle of an advanced spherical hydrostatic bearing with a pressure-tracing system is introduced, which is suitable for large-duty rotary forging presses. Compared with conventional hydrostatic bearings, it possesses many advantages, such as greater stiffness, a longer working life and an easier selection of throttle valves. The algorithms of its main parameters are proposed, including pressure ratio, effective loading area of the oil recess, thickness of oil membrane, etc. Finally, an example is given to support these algorithms.

Dynamic Force Response of Spherical Hydrostatic Journal Bearings for Cryogenic Applications

Hydrostatic journal bearings are ideal elements to replace roller bearings as rotor support elements in cryogenic lurbomachinery. These bearings will be used for primary space-power applications due to their long lifetime, low friction and wear, large load capacity, and direct stiffness and damping force coefficients. The performance characteristics of turbulent flow, orifice compensated, spherical hydrostatic journal bearings are presented. These bearings allow tolerance for shaft misalignment without force degradation and are able to support axial loads, thus providing a design configuration which could be used efficiently on high-performance turbomachinery. Bulk-flow mass and momentum equations for the motion of a variable properties liquid on the thin film bearing lands are solved numerically. Predictions of load capacity and force coefficients for a six recess, spherical hydrostatic bearing in a liquid oxygen environment are presented. Fluid film axial forces and dynamic coefficients of a magnitude a...

Fluid Inertia Effects on the Characteristics of Spherical Hydrostatic Bearings : Part 2 Stability

Based on a first-order perturbation solution in a modified Reynolds number, an analysis is presented to determine the fluid inertia effects on the stability characteristics of a spherical hydrostatic bearing that has continuous spherical surface. This analysis demonstrates that fluid inertia effects increase the stability threshold speed and that the increase in stability threshold depends on the inertia parameter δ=ρω2r02/p★ (ρ=lubricant density, ω=rotational angular velosity, r0=radius of sphere, p★=ambient pressure). It is found that centrifugal effect on load capacity is much greater than the other inertial effects, whereas centrifugal effect on dynamic coefficients is much smaller than the other inertial effects.

Fluid Inertia Effects on the Characteristics of Spherical Hydrostatic Bearings : Part 1 Bearing Forces

Based on a first-order perturbation solution in a modified Reynolds number, an analysis is presented to determine the fluid inertia effects on the dynamic characteristics of a spherical hydrostatic bearing that has a continuous spherical surface. This analysis demonstrates that fluid inertia influences the load capacity and dynamic properties. The corrections to the conventional elastic and damping coefficients derived on the assumption that inertia forces are negligible, are found not too small to neglect when inertia parameter δ=ρω2r02/p★>0.1 (ρ=lubricant density, ω=rotational angular velocity, r0=radius of spherical bearing, p★=ambient pressure). And the acceleration coefficients may become significant when the displacement of a rotor from the bottom of the bearing is smal1.

Fluid Inertia-Effects on the Characteristics of Spherical Hydrostatic Bearings : 2nd Report, Stability

回転体の高速化に伴い流体によって潤滑された軸受の特性は潤滑剤の慣性力の影響を受けることが予想される. 本論文では, 前報で求めた慣性力を考慮した軸受反力を用いて, 軸受の安定性について調べ, 慣性力によって軸受の安定性が増加することを明らかにしている. また, 慣性力のうち負荷容量に及ぼす影響の大きい遠心力の, 安定性に及ぼす影響などについて検討している.

Fluid Inertia Effects on the Characteristics of Spherical Hydrostatic Bearings : 1st Report, Bearing Forces

回転体の高速化に伴い流体によって潤滑された軸受の特性は潤滑剤の慣性力の影響を受けることが予想される. 本論文では, 主として静圧球面軸受の動特性に及ぼす慣性力の影響を検討し, レイノルズ数が比較的小さい場合にも, その影響が表われることを明らかにしている.

Static and Dynamic Behavior of Spherical Hydrostatic Bearings: Theory and Experiments

A static and dynamic analysis is carried out for spherical hydrostatic bearings under conditions of incompressible flow. The usual static theory is shown to need the addition of quadratic loss effects in order to agree with experiments. Computer models of static and dynamic behavior agree well with experimental data. Procedures for estimating stiffness and damping are presented taking the extra quadratic losses into account. Comparison with circular recess bearings shows that spherical bearings appear capable of higher damping ratio for the same size bearing.

Design data and a manufacturing technique for spherical hydrostatic bearings in machine tool applications

Spherical thrust bearings are used to carry loads in radial and axial directions. They have a low resistance to tilting movements as required for self-aligning applications, and have an advantage where large bearings with small operating clearances are required. This paper compares six recess and six pad partial spherical bearings and gives design data for six recess bearings. The effects of eccentricity ratios, attitude angles and load angles are discussed. A manufacturing method is described, including details of the eroding technique used to produce the high pressure recesses. It is concluded that multirecess bearings will usually be preferred, the pressure ratio should be 0·5. Recommendations are made concerning design of the bearing geometry.

Design of fitted spherical hydrostatic bearings

Design of fitted spherical hydrostatic bearings

Design of fitted spherical hydrostatic bearings

The fitted spherical has several advantages over the positive clearance bearing, the most important being its ease of manufacture. A range of application are outlined together with charts and examples to aid design.

Single recess spherical hydrostatic bearings

Single recess spherical hydrostatic bearings