Hydrostatic Thrust Bearing Research Articles

ON THE STATIC ANALYSIS OF ANNULAR RINGH HYDROSTATIC THRUST BEARINGS LUBRICATED WITH COUPLE STRESS FLUIDS

In the present theoretical analysis, the static properties of the annular ring hydrostatic thrust bearings have been investigated. The lubricant in the system has been taken as non-Newtonian couple stress fluids. The effects of centrifugal inertia and couple stresses on the film pressure, load capacity and lubricant flow rate have been studied and a good agreement of the present results with the earlier established results has been observed. Analytic solution for pressure distribution has been obtained in the analysis taking into account, the influence of centrifugal inertia in the recess region. The effect of couple stress on pressure was found to be dependent on central recess radius but the decreasing load capacity and flow rate with the increase of couple stress parameter was observed in the analysis. Load capacity was also observed to be higher with the recess radius closer to the axis of the bearing.

Performance of Hydrostatic Textured Thrust Bearing with Supply Holes Operating with Non-Newtonian Lubricant

ABSTRACTThe present article proposes a technique to improve the performance of textured hydrostatic thrust bearings with the use of oil supply holes. The article provides a comparison between smooth and surface-textured hydrostatic thrust bearings. To get an accurate prediction of the caviation regime, the Jakobsson-Floberg-Olsson (JFO) mass conservation algorithm has been used instead of the Reynolds boundary conditions. It has been observed that surface texture results in a significant decrease in friction power loss along with an improvement in other performance parameters. The study also reveals that the location of the supply hole for the lubricant system significantly affects the bearing performance.

A new optimization algorithm for solving complex constrained design optimization problems

ABSTRACTThis article presents the performance of a very recently proposed Jaya algorithm on a class of constrained design optimization problems. The distinct feature of this algorithm is that it does not have any algorithm-specific control parameters and hence the burden of tuning the control parameters is minimized. The performance of the proposed Jaya algorithm is tested on 21 benchmark problems related to constrained design optimization. In addition to the 21 benchmark problems, the performance of the algorithm is investigated on four constrained mechanical design problems, i.e. robot gripper, multiple disc clutch brake, hydrostatic thrust bearing and rolling element bearing. The computational results reveal that the Jaya algorithm is superior to or competitive with other optimization algorithms for the problems considered.

Theoretical research on mechanical property of rectangular oil pad in hydrostatic thrust bearing based on constant flow

Purpose This paper aims to research the lubrication performance of large-size rectangular oil pad in hydrostatic thrust bearing for heavy computer numerical control (CNC) vertical lathe. Design/methodology/approach The research establishes the mathematical models of velocity, flux and pressure fields, etc., for lubrication performance distribution, and analyzes its load-bearing behavior. Findings When hydrostatic thrust bearing’s rotating speed is within ω1-ω2, the oil flow generated by plate’s relative motion is greater than that generated by pressure difference and centrifugal force, and in the opposite direction, making it not easy to emit friction heat, so the rotating speed range ω1-ω2 should be avoided for bearing. Originality/value The research provides powerful theoretical basis for the structure design, operating reliability and practical application of large size rectangular oil pad hydrostatic thrust bearing, and realizing the prediction of its lubrication performance.

Numerical Optimization Of A Distributor Valve

AbstractIn this paper a non-linear optimization method is used to improve the design of a distributor valve. The distributor valve is an important component in a radial piston hydraulic motor, and optimization of the design to minimize power losses is an interesting way to increase efficiency. The main function of a distributor valve is to supply the pistons with a pressurized flow and to return oil during rotation. At the same time the distributor valve acts as an externally pressurized lubricated thrust bearing, in order to separate the rotating parts from the motor case. The bearing acts as a hydrostatic annular multi-recess plane thrust bearing, with different recess pressures. The separating force of the bearing is balanced hydrostatically by the pressure that is applied and springs. Losses will occur in the contact between the parts in the distributor valve, due to friction and leakage.This paper shows that modern optimization methods can be used as an effective tool to create new designs and to mod...

大径シリコンウエハ加工用ロータリ研削盤の開発（第１報：水静圧ロータリテーブルの基本特性の検討）

Increasing of Si wafer diameter from φ300 mm to φ450 mm is required to enhance productivity of semiconductor devices. The authors developed a high stiff rotary grinding machine, which consists of a rotary table system and a wheel spindle system. These system are rigidly clamped using three ball screws and kinematic couplings. This paper investigates a basic design and the performances of the rotary table system equipped with constant flow water hydrostatic bearings. A fluid analysis around bearing pad was attempted by using the finite volume method in order to enhance a static stiffness of water hydrostatic thrust bearing. Performances of the developed rotary table was evaluated experimentally and compared with the analyzed value. The measured static stiffness and the numerical analyzed static stiffness ware 1.96 kN/μm and 1.97 kN/μm, respectively under the flow rate of each bearing pads Q=30 mL/min.

対向式水静圧スラスト軸受の変位制御系の設計

対向式水静圧スラスト軸受の変位制御系の設計

An Investigation into the Mechanical Properties of Hydrostatic Thrust Bearing for Constant Flow Circular Ring Oil Pad

An Investigation into the Mechanical Properties of Hydrostatic Thrust Bearing for Constant Flow Circular Ring Oil Pad

弾性ヒンジを用いたアクティブ制御型油静圧スラスト軸受に関する研究

弾性ヒンジを用いたアクティブ制御型油静圧スラスト軸受に関する研究

Velocity Characteristic on Oil Film Thickness of Multi-Pad Hydrostatic Thrust Bearing with Circular Recess

Velocity Characteristic on Oil Film Thickness of Multi-Pad Hydrostatic Thrust Bearing with Circular Recess

Experimental and Numerical Study on the Temperature Performance of High-Speed Circular Hydrostatic Thrust Bearing

Experimental and Numerical Study on the Temperature Performance of High-Speed Circular Hydrostatic Thrust Bearing

Effects of Grooving in a Hydrostatic Circular Step Thrust Bearing With Porous Facing

Effects of grooving in a porous faced hydrostatic circular step thrust bearing are investigated using a mathematical model based on the narrow groove theory (NGT). It is shown that enhancement of load capacity by grooving the step is possible at moderate level of permeability of the porous facing. Load capacity drops sharply with the increase of porous facing thickness. However, this drop in load capacity occurs mostly within a small thickness of the porous facing. Considering the coupled effects of permeability and inertia, it is recommended that the dimensionless step location should be 0.5–0.8 and the dimensionless step height should be less than five to take advantage of grooving. The groove geometric parameters such as groove inclination angle, fraction of grooved area and groove depth corresponding to the maximum load capacity are found to be the same for both with and without porous facing. However, with porous facing, the sensitivity of the load capacity on the groove parameters reduces. At high level of permeability, the effects of grooves may become insignificant because of high seepage flow through the porous facing.

S1310103 対向式水静圧スラスト軸受の変位制御系の検討

S1310103 対向式水静圧スラスト軸受の変位制御系の検討

Comparative Study on Pressure Field of Hydrostatic Thrust Bearing with Different Recess Shapes

A comparative study on pressure field of hydrostatic thrust bearing with sector recess, rectangular recess, ellipse recess and I-shaped recess is carried out in order to solve the deformation of the hydrostatic thrust bearing. The Finite Volume Method has been used to compute three-dimensional pressure field of gap oil film between the rotation worktable and the base. This study theoretically analyzes the influence of recess shape on the bearing pressure characteristic according to Computational Fluid Dynamics (CFD) and lubricating theory. It has revealed its pressure field distribution law. The simulation results indicate that an improved characteristic will be affected by recess shape easily. Through this method, the safety of a hydrostatic thrust bearing with different recesses can be forecasted, and the optimal design of such products can be achieved, so it can provide reasonable data for design, lubrication, and experiment and deformation computation for hydrostatic thrust bearing.

Feasibility Study on Design of Spindle Supported by High-Stiffness Water Hydrostatic Thrust Bearing

The machining accuracy of ultra-precision machine tools relies on the performance of the spindle and linear table. The machining accuracy of ultra-precision machine tools is now at the level of several tens of nanometers. In order for ultra-precision machine tools to achieve machining accuracy, a precise spindle system is indispensible. High bearing stiffness is particularly important to minimize displacement due to the cutting force. This paper considers a spindle design supported by high-stiffness water hydrostatic thrust bearings. An objective of this study is to design a precision spindle supported by water hydrostatic thrust bearings with 1 kN/µm bearing stiffness. The bearing restrictors are chosen so that the highest stiffness can be obtained for given bearing parameters. The influences of gap sizes and supply water pressure on the bearing stiffness are presented. Based on the feasibility study done on the design of highstiffness water hydrostatic thrust bearings, the spindle is designed and developed. The influences of the water pressure on the spindle deformation and bearing stiffness are also investigated.

Performance of hydrostatic tilted thrust pad bearings of various recess shapes operating with non-Newtonian lubricant

Hydrostatic thrust bearings are an integral part of hydroelectric power stations. These bearings are usually designed to work under parallel operation, but tilt is inevitable due to manufacturing errors, assembly errors, structural vibrations and structural deformations. Owing to the advent of latest advancements in manufacturing techniques, any geometric shape of recess can be easily manufactured and the designer has a greater flexibility. The geometric shape of recess significantly affects the performance of a bearing. Therefore, the present study is aimed to numerically analyze the influence of the tilt and recess shape on the static and dynamic performance characteristics of the hydrostatic thrust pad bearing system having Rabinowitsch fluid model lubricant. The lubricant obeying Rabinowitsch fluid model with tilt makes the Reynolds equation highly non-linear therefore, finite element method is used to analyze. Three different types of recess shapes of equal area A¯b/A¯oc=4 have been analyzed to model hydrostatic thrust pad compensated by orifice compensator. The numerically simulated results indicate that the tilt angle significantly affects the dynamic and static characteristic parameters. The value of pocket pressure and fluid film reaction of a hydrostatic thrust pad bearing has been found to significantly decrease with tilt whereas the value of lubricant flow, fluid film stiffness coefficient and fluid damping coefficient increase with tilt.

Influence Research of Cavity Shapes on Temperature Field of Multi-pad Hydrostatic Thrust Bearing

In order to compute the thermal deformation of the hydrostatic thrust bearing in the heavy type CNC equipments, a numerical research concerning temperature field of multi-pad hydrostatic thrust bearing having sector cavity, rectangular cavity, Ishaped cavity and ellipse cavity is described. Three-dimensional temperature field of gap fluid between the rotation worktable and the base has been simulated by using Finite Volume Method of CFX. This study analyzes the influence of cavity shape on the bearing temperature performance according to computational fluid dynamics and lubricating theory. It has revealed its temperature distribution. The simulation results demonstrate that an improved characteristic will be affected by cavity shape easily. Through this method, the safety of a multi-pad hydrostatic thrust bearing having different cavities can be forecasted, and the optimal design of such products can be achieved, so it can provide reasonable data for design, lubrication, experience and thermal deformation computation for hydrostatic thrust bearing in the heavy CNC equipments.

Static characteristics of a water-lubricated hydrostatic thrust bearing using a membrane restrictor

It is well known that water does not pollute the environment as much as oil, but it has lower viscosity. We investigate the static characteristics of a water-lubricated hydrostatic thrust bearing using a membrane restrictor to achieve higher stiffness and lower power consumption at high speeds. The static characteristics of the proposed hydrostatic thrust bearing were studied numerically and experimentally for a nonrotating shaft. In the numerical calculations, the orifice effect was taken into account at the inlet of the viscous resistance area of the membrane restrictor. We found that the proposed water-lubricated hydrostatic thrust bearing could achieve a very high static stiffness by using the membrane restrictor, and the numerical and experimental results showed good agreement.

The Numerical Analysis of the Velocity and Pressure Distribution of the Oil Film in Heavy Hydrostatic Thrust Bearing

To study the velocity and pressure distribution of the oil film in a heavy hydrostatic thrust bearing, a mathematical model of the velocity is proposed and the finite volume method (FVM) has been used to simulate the flow field under different working conditions. Some pressure experiments were carried out and the results verified the correctness of the simulation. It is concluded that the pressure distribution varies small under different rotation speed when the surface load on the workbench is constant. But the velocity of the oil film is influenced greatly by the rotation speed. When the rotation speed of the workbench is as quick as enough, the velocity of the oil film on one radial side of the pad will be zero, that is to say the lubrication oil will be drained from the other three sides of the recess.

Research on Dynamic Pressure of Hydrostatic Thrust Bearing Under the Different Recess Depth and Rotating Velocity

In order to solve the loading capacity of the hydrostatic thrust bearing, a numerical simulation concerning dynamic pressure of multi-pad hydrostatic thrust bearing under the different recess depth and rotating velocity is been described. Three-dimensional dynamic pressure field of gap fluid between the rotational worktable and the base has been simulated by using the Computational Fluid Dynamics. This study theoretically researches the influence of recess depth and rotating velocity on dynamic pressure of the bearing according to the lubricating theory and Finite Volume Method, and the simulation results indicate that an improved characteristic will be affected by recess depth and rotating velocity easily. Through this method, the optimal loading capacity of such products can be achieved.