新型偏心静压向心轴承的性能研究

提出一种组合油腔结构的新型偏心静压向心轴承，通过数值计算给出矩形腔、岛式腔和组合腔结构的轴承性能比较，表明新型组合腔结构轴承的承载能力和刚度系数均最高。     

腔内孔式回油液体静压轴承回转性能(动压效应)的研究

液体静压轴承是利用专用的供油装置,以一定的压力把润滑油送到轴承中去,在轴承油腔内形成具有压力的润滑油层,将轴浮起而具有承载能力。而液体动压轴承则需要轴与轴承之间有一定的相对运动才能在轴承间隙中形成一层具有压力的油膜,建立承载能力。液体静压轴承承载能力的大小主要取决于轴承参数以及油泵的供油压力,在小偏心的情况下.一般认为转速与承载力关系不大。然而,静压轴承在较大偏心率使用时,当轴承与主轴有相对运动的场合下,能否象动压轴承那样,把动压效应也考虑进去,以获得较高的承载能力、刚度等,这就是本文所要讨论的问题。     

沟槽静压轴承试验与计算

沟槽式液体静压轴承是一种采用间隙很小的沟槽作为节流器的无油腔的静压轴承。它除了具备一般静压轴承的基本性能外,在旋转下使用时,由于轴承内不设油腔,因而能产生较大的动压效应,性能比普通静压轴承有所提高。国外在60年代、我国在70年代已开始使用,效果较好。沟槽轴承的设计计算最初只考虑静态(不包括动压效应)下的计算,近代电子计算机使设计计算工作深入一步,能把动压效应也考虑了,因此对这种轴承的性能能有进一步认识。本文通过试验和分析计算去了解沟槽轴承的特性。     

静动压轴承的原理及其应用

近几年来,静动压轴承的研制成功,为精密机床主轴系统提供了新型的轴承。该轴承兼有静压轴承和动压轴承的优点。笔者将台阶式油楔静动压轴承的原理,应用于精密磨床砂轮主轴轴承的改装中,取得了较好的效果。一、台阶式油楔静动压轴承图1为台阶式油楔静动压轴承的结构简图。h_0为轴承封油面和主轴间的半径间隙,h_1为轴承油腔表面与主轴间的深度。压力油P_s进入轴承的环槽中,通过油腔h_1和间隙h_0沿轴向流出轴承,回到油池. 1.静压效应的形成如图2a,当主轴中心与轴承中心相重合时,压力油P_s通过上下油腔的压降相等,压力分布如图所示。其中,P_上=P_下,因此轴承上下油腔作用在主轴上的     

读者信箱

《润滑与密封》编辑部: 我们有两个问题不清楚,敬请指导。(1)对于你刊“腔内孔式回油液体静压轴承回转性能(动压效应)的研究”(1979年第3期)一文中谈到的“将过去常用的静压轴承油腔结构稍加改动,使其油腔之间径向油封面局部加大”,其加大的前提是什么?径向油封面加大到多少为宜?加大后会不     

周向无回油槽油腔式静压轴承分析计算及优化设计

周向无回油槽油腔式静压轴承能充分利用轴向和周向封油面上的动压效应,以提高轴承的承载能力。本文讨论任意油腔数的静压轴承的程序设计,利用具有较强通用性的变步长有限差分法,直接求解雷诺方程来进行轴承的分析计算。优化设计采用复合形法,以单位承载量下的功耗最小为目标函数。为使优化设计成为切实可行,采用了高低精度迭代技术、自动选择合理超松驰因子等一系列有效措施,可在IBM-PC微型计算机上运算,获得了经济机时,可供设计人员直接调用,特别适合我国国情。     

动静压轴承油腔结构对性能的影响

本文讨论静压轴承及动静压轴承的回油槽、油腔形状、封油面等油腔结构形式对轴承的动静压承载能力及抗振性等的影响,指出了提高轴承性能的若干方法。     

精密阶梯形液体动静压轴承（一）

液体动静压轴承在结构上既有静压轴承的特征,又有产生流体动力的基本条件。在静止时,由于静压的作用可使主轴悬浮,在旋转时又会形成动压。因此,它与液体动压轴承相比,液体动静压轴承具有起动力矩小、能在一定的载荷下大范围地调节速度的特点;与液体静压轴承相比,液体动静压轴承充分利用轴承动压效应,从而具有高的承载能力和动刚性,且抗振性     

动静压滑动轴承的稳定性分析

根据有限元法对几种类型动静压滑动轴承的计算结果讨论了它们静态承载能力及动态稳定性，并将３６０度圆柱孔动压滑动轴承和油腔式静压滑动轴承的静、动特性与几种动静压滑动轴承的静、动特性进行了对比，从理论上确定了动静压滑动轴承的承载能力优于油腔式静压滑动轴承，动静压滑动轴承的动特性优于３６０度圆柱孔动压滑动轴承。     

小孔式动静压滑动轴承稳定性分析

用伽辽金法及摄动理论建立了小孔式动静压滑动轴承的有限元模型，并对其进行了静，动特性分析。分析结果表明，小孔式动静压轴承载能力明显优于油腔式静压轴承，其动特性也优于几何尺寸相同的圆柱孔动压滑动轴承。     

Characteristics of a hybrid journal bearing with one recess: Part 1: Dynamic considerations

A fluid film hybrid journal bearing with one recess, as used in tandem cold rolling mills, is studied theoretically in two ways. The dynamic response of the hybrid bearing, under isothermal conditions due to the decrease in hydrostatic pressure, is considered and presented in Part 1 of the study, while the thermal effects on the load capacity, temperature distribution, etc of the bearing will be dealt with and described in Part 2.In this paper, the dynamic behaviour of the journal due to the decrease in hydrostatic pressure is presented in the form of transient orbits and squeezed-film speeds, which are shown to be dependent on the initial equilibrium conditions. In the analysis, when the recess pressure is dropped below the hydrodynamic pressure generated by the fluid film, it is found to be difficult to obtain a convergent solution. The dynamic response of the bearing, due to the shut-off of external pressure is, therefore, simulated by the dynamic behaviour of the journal due to a series of pressure drops in arbitrary time intervals. The results show that the journal is quite stable in such conditions.     

Performance of membrane compensated multirecess hydrostatic/hybrid flexible journal bearing system considering various recess shapes

The paper describes a theoretical study concerning the performance of an externally pressurized multirecess hydrostatic/hybrid flexible journal bearing system by varying the geometric shape of recess and using the membrane flow valve restrictor as a compensating element. The four different recess geometries of the bearing studied in the present study are a square recessed bearing, a circular recessed bearing, an elliptical recessed bearing and a triangular recessed bearing. The equation governing the flow of lubricant in a journal bearing together with 3D elasticity equation and restrictor flow equation are solved by using the Finite Element Method. The study describes the effect of recess shape, bearing flexibility and a method of compensation on the performance characteristics of a hydrostatic/hybrid journal bearing system. A comparative performance of the membrane compensated hydrostatic/hybrid journal bearing system has also been studied vis-à-vis capillary, orifice and constant flow valve restrictors. The results presented in this study amply demonstrate that the shape of recess/pocket of a hydrostatic/hybrid flexible journal bearing system affects the performance of the bearing quite appreciably and a proper selection of recess shape along with a suitable compensating device is needed to get an improved performance from the bearing.     

A new basis for the optimization of hybrid journal bearings

A design strategy is presented for hybrid hydrodynamic/hydrostatic journal bearings which maximizes the hybrid load for minimum total power dissipation. It is shown that the detailed design of hybrid bearings is quite different from the design of recessed hydrostatic bearings. It is found that design for hybrid operation may lead to substantial increases in load support with significantly less total power dissipation than would be required if the designs were developed from hydrostatic bearing procedures.A new technique for optimizing hybrid journal bearings is presented. The method involves the comparison of the bearings to be optimized with a reference bearing on the basis of load/total power, load/pumping power and load/flow.     

卧式水电机组局部多油楔径向滑动轴承研究

针对卧式水电机组用径向滑动轴承载荷日益提高的现状,设计一种局部多油楔瓦面结构的径向滑动轴承。通过联立求解膜厚方程、雷诺方程、密度方程、黏度方程、能量方程和固体热传导方程等,获得轴承的热流润滑特性,并与椭圆径向滑动轴承的热流特性进行对比。结果表明,局部多油楔径向滑动轴承具有较大的动压承载区域和较小的油膜压力梯度以及较低的油膜温升,可以大幅度提高轴承的承载能力。     

Hybrid journal bearings with particular reference to hole-entry configurations

There is a spectrum of pressure-fed journal bearings ranging from the purely hydrostatic bearing characteristics, ie zero speed operation, to the purely hydrodynamic bearing characteristics which depend completely on speed. Between these two extremes, hybrid bearing characteristics rely on mixed modes of external pressurisation and speed-dependent pressurisation. Large high speed hydrodynamic bearings require the lubricant to be pumped under pressure for temperature control. It is therefore attractive to use this external source of pressure to enhance the start-up performance by reducing wear and improving stability. Hybrid bearings offer the possibility of improving on both the zero-speed characteristics of hydrostatic bearings and on the whole range of speed characteristics of hydrodynamic bearings. It is concluded that hole-entry bearings may be particularly effective when compared with other bearing configurations for good load support and low energy consumption, when used in any of the four modes of operation including: zero-speed hydrostatic mode; high-speed hydrodynamic mode; zero and high-speed hybrid mode; and jacking mode where areas are pressurised for start-up. A modification to the procedure for solving the Reynolds equation is introduced to cope with cavitated regions. The technique presented for solving the bearing pressures and cavitation boundaries is efficient and has relevance to any type of liquid film bearing     

Design of multirecess hydrostatic oil journal bearings

This paper presents computer generated design data in terms of load capacity and oil flow for multirecess hydrostatic journal bearings. The Reynolds equation for a finite bearing was solved on a high speed digital computer satisfying appropriate boundary conditions and using the finite difference method. Results for various L/D ratios, recess to bearing area ratios, number of recesses etc are presented for capillary and orifice compensated bearings.     

Static performance of hydrostatic air bump foil bearing

A few years ago, a hydrostatic air foil bearing using compression springs as elastic foundation was firstly introduced by Kim and Park [1]. This paper presents recent experimental results on load capacity of a new hydrostatic air foil bearing made of corrugated bump foils. The new hydrostatic air foil bearing was designed with higher structural stiffness than the first design by Kim and Park [1]. A new test rig was also designed and constructed to measure load capacity of the bearing at higher speeds. The new test results indicate the hybrid operation has similar load capacity to that of hydrodynamic operation at high speeds due to dominance of hydrodynamic pressure. However, comparative tests at low speed (10,000 rpm) showed noticeable increase of load capacity in hydrostatic air foil bearing, manifesting effective hydrostatic levitation feature at low speeds.     

Modeling of Gas Thermal Effect Based on Energy Equipartition Principle

In the present article, a gas thermal effect is modeled based on the energy equipartition principle. Two new independent state equations for an ideal gas are developed that provide a new way to analyze thermal effects in gas lubrication. Furthermore, the energy equation is derived for gas lubrication and the analysis of thermal effects is carried out on a gas spiral thrust bearing and a gas hydrostatic journal bearing. The results show that gas temperature increases significantly in the lubricated region at high speed for both the thrust and hydrostatic journal bearings, and the thermal effect positively influences the load capacity of the thrust bearing. The gas expansion effect makes the gas temperature decrease in the hydrostatic journal bearing, and the gas temperature decreases with an increase in the inlet pressure.     

Orifice compensated multirecess hydrostatic/hybrid journal bearing system of various geometric shapes of recess operating with micropolar lubricant

The objective of the present paper is to study analytically the performance of four-pocket orifice compensated hydrostatic/hybrid journal bearing system of various geometric shapes of recess operating with micropolar lubricant. The modified Reynolds equation for micropolar lubricant is solved using FEM and the Newton-Raphson method along with appropriate boundary conditions. The results suggest that the influence of micropolar effect of lubricant on bearing performance is predominantly affected by the geometric shape of recess and restrictor design parameter. Therefore, the bearing designer must judiciously choose an appropriate geometric shape of recess in order to get an overall enhanced bearing performance.