轴承游隙的选择

轴承游隙的选择正确与否,对机械运转精度、轴承寿命、摩擦阻力、温升、振动与噪声等都有很大的影响。根据轴承的使用条件,选择最合适的游隙值,具有十分重要的意义。     

薄壁轴承径向游隙的测量

由于薄壁轴承内、外圈的壁厚比较薄,采用加载方式测量轴承的径向游隙时,容易导致被测轴承的外圈变形,影响径向游隙的测量值。根据薄壁轴承的特点,介绍了无负荷测量薄壁轴承径向游隙的方法,保证了薄壁轴承的质量要求。     

圆柱滚子轴承径向工作游隙的影响因素及选择

以圆柱滚子轴承为例，从理论上分析了影响滚动轴承径向工作游隙的主要因素，给出选择轴承径向工作游隙的计算公式并进行了实例计算。克服了传统的通过定性分析选用推荐值的方法确定轴承径向工作游隙的局限性，以保证轴承在具体的工作条件下处于最佳的工作游隙状态。     

轴承径向游隙分析

通过滚动轴承制造、安装、运行等因素对轴承寿命、温升和噪声影响的分析，提出了轴承配合游隙的合理量值。     

数字式轴承游隙测量仪

本文介绍了一种代替传统轴承游隙测量装置的新型仪器─-数字式轴承游隙测量仪,并简要叙述了它的基本原理,软件、硬件设计思想,功能、先进性和重要的应用价值。     

大型柔性轴承的设计及游隙的测量与计算

在某些对重量要求严格控制的场合,必须对各零、部件进行减重设计,作为转动副的轴承也不例外,经过减重设计的轴承称之为柔性轴承,文中提出了大型柔性轴承的几点设计要素及轴承游隙的测量和计算的方法。     

A method of reducing windage power loss of a high-Speed motor using a viscous vacuum pump

A new structure for reducing the windage power loss of a high-speed rotor using a spiral grooved viscous vacuum pump combined with an aerodynamic step thrust bearing is proposed. The proposed structure can pump out the air from within the sealed space of the motor housing by using the pumping effect of the spiral grooves and thereby reduce the windage power loss of the rotor. In addition, a small gap was automatically formed between the rotor and the viscous vacuum pump by using the force balance between the aerodynamic step thrust bearing and the elastic material supporting the flat plate of the vacuum pump. It was numerically shown that the proposed structure could reduce the pressure in the sealed space of the motor housing to 0.02 MPa at 30,000 rpm at a gap of 10 μm. In addition, the calculated results at 10,000 rpm were compared with the experimental results and showed good agreement and the proposed structure was very useful in reducing the windage power loss of a high-speed motor.     

预紧双列调心滚子轴承径向游隙控制

以双列调心滚子轴承为例,从理论上分析预紧滚动轴承径向工作游隙的影响因素以及工作游隙对轴承使用寿命的影响,并给出轴承预紧前最佳原始游隙的计算公式.实践证明这种方法可以保证轴承在具体的工作条件下处于最佳的工作游隙状态,达到最长的使用寿命.     

Discharge coefficient influence on the performance of aerostatic journal bearings

Aerostatic journal bearings need externally pressurized air. The discharge coefficient is usually assumed constant for sonic and subsonic flow conditions. However, some authors found that it is variable as a function of the pressure ratio, orifice throat discharge and supply pressures. The present study is a theoretical investigation of the discharge coefficient influence on the performance of aerostatic journal bearings. The Reynolds equation for compressible fluids is solved by the finite element method with triangular linear elements. For 0.5 eccentricity ratio, the bearing load carrying capacity difference is 0.5%, although the bearing total mass flow rate difference is 7.4%.     

Hydrostatic air foil bearings: Analytical and experimental investigation

Air foil bearings have been used in various micro-turbomachinery applications. One of the critical technical challenges in extending the operating envelope of the air foil bearing to larger systems than current applications is the issue of coating wear on the top foil and rotor during starts/stops.This paper reports the design, construction, and testing of the first hydrostatic air foil bearing (HAFB). The HAFB showed higher load capacity with much less air consumption than the hydrodynamic counterpart, which is a noticeable advantage of HAFB in efficiency and cooling capacity. In addition, start torque was very small and comparable to the friction torque of steady-state hydrodynamic operation. The small start torque clearly indicates that the HAFB can help to eliminate the wear problem that has been a chronic failure mode in heavily loaded air foil bearings.A simple analytical model for prediction of top foil deflection and sagging effects under hybrid (both hydrostatic and hydrodynamic) mode was developed. The new top foil deflection model showed very good agreement with published experimental data. The top-foil deflection model and associated bump dynamics were integrated into time-domain orbit simulations to predict imbalance responses of a rigid rotor supported by HAFBs.     

角度偏差对过盈联接强度的影响

在分析母线角度偏差引起配合长度上压力变化的基础上。提出在母线角度不同时计算圆锥过盈联接圆周力矩的敷学模型,论述母线角度偏对相对圆周力矩的影响,为圆锥过盈联接的设计提供了重要的理论参考依据。     

大货车后视镜震动工况原因实测实验及仿真研究

大货车后视镜的震动会通过影响驾驶员的操作而引起安全事故。本文通过运用实测的大货车震动数据,分析大货车后视镜震动的主要工况影响因素,提出建立大货车后视镜动态震动检测体系,该体系由不同路况震源检测体系、后视镜震动空气动力学性能检测体系组成,以全面检测大货车后视镜工作状态的震动影响,文章最后提出了一种综合测试大货车后视镜震动状态的测试台设计思路。     

Analysis of gas foil bearings integrating FE top foil models

Gas foil bearings (GFBs) find widespread usage in oil-free turbo expanders, APUs, and micro gas turbines for distributed power due to their low drag friction and ability to tolerate high-level vibrations. The performance of GFBs depends largely on the support elastic structure, i.e. a smooth foil on top of bump strips. Conventional models include only the bumps as equivalent stiffnesses uniformly distributed around the bearing circumference. More complex finite element (FE) models couple the elastic deformations of the 2D shell or 1D beam-like top foil to the bump deflections as well as to the gas film hydrodynamics. Predictions of journal attitude angle and minimum film thickness for increasing static loads and two journal speeds are obtained for a GFB tested decades ago. For the GFB studied, 2D FE model predictions overestimate the minimum film thickness at the bearing centerline, while underestimating it at the bearing edges. Predictions from the 1D FE model compare best to the limited tests data, reproducing closely the experimental circumferential wavy-like film thickness profile. Predicted stiffness and damping coefficients versus excitation frequency show that the two FE models result in slightly lower direct stiffness and damping coefficients than those from the simple elastic foundation model.     

Development of externally pressurized small-size conical-shaped gas bearings for micro rotary machines

We have developed externally pressurized small-size conical shaped gas bearings for micro rotary machines such as gas blowers, compressors, and medical devices. The bearings are lightweight and enable machines and devices to be downsized by reducing the number of parts, since the journal and thrust loads can be supported by a pair of bearings. The conical bearings (diameters 8 mm and 10 mm) were designed and the manufacturing techniques were considered. The bearing type is a double-row inherent orifice bearing with four feed holes per row. The shape accuracy of the manufactured bearings is within the design limits, being less than 0.005 mm in both roundness and cylindricity. The surface roughness (arithmetic average roughness) of the parts is 0.0002 mm. The static characteristics were calculated and validated by testing on manufactured bearings. Comparative agreement was obtained between the measured and designed values. The proposed calculation method presents as a relatively simple approach for predicting the bearing characteristics. The test rotor exceeded 350 Hz (21,000 rpm) in the rotational test, and whirl vibration was absent. During testing, the maximum rotor vibration amplitude was 0.0125 mm (corresponding to an eccentricity ratio of 0.89).     

列车圆柱滚动轴承内外圈的配合和原始径向游隙对运行安全的影响

针对我国目前在列车中使用的圆柱滚动轴承与轮轴及座孔配合中的问题及其目前实践中采用的原始径向游隙的合理性进行了分析，并提出原始径向游隙的取值，不应一概而论，应随车速、载荷和原始配合大小而取不同值。     

变幅外摆线的数学特性和摆线针轮行星传动可选择参数的优化(一)

从外切外摆线与内切外摆线的等同条件出发,推导出以下两种外摆线滚圆与基圆的中心距和变幅系数为已知参数的参数方程。从摆线针轮行星传动(以后简称为摆针传动)的基本参数出发,得出偏心距α=1时以针轮齿数z和短幅系数k1为已知参数的基本参数方程,而任意偏心距下的摆线齿形及其参数方程仅仅是基本方程所表达的基本齿形以偏心距α为倍数的线性放大或线性缩小。从针齿半径取值与摆线最小曲率半径相联系的观点出发,推算出以摆针传动承载能力最大为目标的针径取值系数的最佳值。从摆针传动承载能力大小与传动装置体积大小相联系的观点出发,推算出摆针传动以最小体积取得最大承载能力k1值的优化方法,这种方法概括为求效能体积比最大值ηvmax下的k1值。