Metallurgical and tribological investigations of aluminium bronze bushes made by a novel centrifugal casting technique

Aluminium bronzes have been used as high strength, corrosion and wear resistance alloys for many decades. However, the alloy has a narrow solidification range and a complex nature which has confined its use to a limited field of applications. Published data on the wear characteristics and the metallurgical nature of the alloy system is limited, leaving wide possibilities for research. In the work described in this paper a study has been made of the metallurgical and tribological characteristics of aluminium bronzes conforming to BS 1400 AB2 specification. A novel centrifugal casting technique using a bonded sand lining integrated into a standard rotating die was adapted to cast a series of test bushes. Mechanical and microscopic aspects are studied and an attempt is made to correlate the physical properties with the tribological behaviour of the bushes. The results show that the test behaviour of the test bush was in some respects better than that of commercially produced bushes made by forging techniques. Detrimental embrittlement, due to ‘self annealing’ is significantly reduced by the adoption of the novel centrifugal casting technique referred to above.     

离心鼓风机轴瓦失效分析及预防

D400-15型离心鼓风机是广西柳州某化工集团硫酸厂的关键设备之一.通过对该厂1999年10月投产以来的两台离心鼓风机的轴瓦失效情况进行的统计,将造成轴瓦失效的主要原因分成4类,即:轴瓦质量差、转子动平衡超标、研刮不良以及润滑油油质不佳等.对造成轴瓦失效的主要原因及机理进行了深入的分析,建立了轴瓦失效故障树,并提出了与主要失效原因相对应的预防措施.     

An analysis of the lubrication mechanisms of the bush-type bearings in high pressure pumps

The paper examines the behaviour of the bushes in high pressure ‘bush configuration’ gear pumps. Experimental measurements of the clearances between the end-faces of the gears and the bushes are presented and an analysis of the mechanism of lubrication is given. It is suggested that bush lubrication depends on the surface irregularities at the ends of the gears and on the non-flatness of the bushes.     

The role of transfer and back transfer of metals in the wear of binary AlSi alloys

Binary melts of AlSi alloys were cast into bars 6.25 mm in diameter which were slid against hard steel bushes on a pin-bush machine. Surfaces, subsurfaces and wear debris were examined with a scanning electron microscope. Simulated studies were also carried out using model asperities in wax. The topographies from sliding were compared with those on cutting tools after machining aluminium. The surfaces of wax models were studied for comparison with machined and slid surfaces. Wear rates were measured. Techniques such as X-ray diffraction analysis were used to identify the nature of the surface and subsurface. Heavy loads produce a topography which has the appearance of roof tiles and these indicate near-seizure conditions. The bulk of the wear debris is produced by craze cracking. It is evident that transfer and back transfer of material occur across the sliding interface throughout a wear run. A critical number of layers build up on both members of the friction couple. Wear particles are produced once this number is exceeded. The wear rates of the AlSi alloys are not linear with load and a near-eutectic alloy is the ideal material from the point of view of wear and load-carrying capacity.     

A finite-element analysis of the connecting bolts of slewing bearings based on the orthogonal method

This paper presents an analysis of the main factors affecting the performance of connecting bolts for slewing bearings. For double row four-point contact ball bearings, major factors include the preload, friction coefficient and height of the bushes. First, bolt connection performances with different levels of each factor are calculated with the finite element method (FEM). Then, the calculation results are analyzed with the orthogonal method. The analysis indicates that the preload is the most important factor affecting the bolt connection performance, followed, to a lesser degree, by the height of the bushes. The friction coefficient is the least important factor.     

镶嵌式复合径向滑动轴承的实验研究

对镶嵌式径向滑动轴承进行了实验研究,通过摩擦磨损实验进行了选材,提出了加工该型轴承的制造工艺,并采用台架试验测试了制得的几种镶嵌式径向滑动轴承的承载能力。结果表明：镶嵌式径向滑动轴承的承载能力比普通径向滑动轴承有较大的提高,其中镶嵌PTFE高分子材料的轴承,因PTFE材料能在其对偶件表面形成较为完全的转移膜,改善了轴承润滑性能,使轴承具有较高的承载能力。     

水润滑塑料合金轴承数值分析的多重网格法

由于水润滑塑料合金轴承的特殊性：带有纵向的沟槽和轴承衬(塑料合金)弹性模量低，以及弹流润滑的计算比较复杂，将多重网格法引入到水润滑塑料合金轴承的弹流润滑计算之中，成功地实现了数值解，为其理论研究奠定了基础。     

动压磨头抱轴现象分析与处理

对动压磨头的抱轴现象进行了分析,并针对长五块瓦的抱轴处理过程进行了详细说明.     

Wear of lubricated plastics-based precision pivot bearings and the effect of the surface free energy of polymers

The effect of oil spreading on plastic bushes on the wear of steel-polymer precision pivot bearings was investigated. Analysis of oil spreading allowed a comparative evaluation of the surface free energy of the various polymers used as bush materials to be made. Correlation was found between the influence of lubrication on the wear of the bearings and the spreading velocity of the oil.     

Stability of the rotor supported in gas journal bearings with a chamber feeding system

This paper describes the results of numerical investigations of the stability problem of the rigid symmetrical rotor supported in two externally pressurized gas journal bearings. The bushes of the bearings are mounted on a system of linear springs and viscous dampers. When the stiffness and damping coefficients of these springs and dampers are chosen correctly, it is possible to avoid the self-excited vibrations of the rotor. Such vibrations, which are caused by the phenomenon of a half-synchronic whirl, are the major obstacle to the widespread application of gas bearings. The results of authors numerical experiments have shown that the elastic support of the bearing bushes can be designed as an additional externally pressurized air ring, surrounding the bush. The set of parameters of such a ring is optimal when the bearing has a chamber feeding system.     

CFD在柴油机连杆轴承穴蚀分析和轴承改进中的运用

轴心轨迹是分析轴瓦故障常用方法,根据轴心轨迹图可以判断轴承工作的可靠性,分析轴瓦损坏的原因。但轴瓦故障只能从轴心轨迹形状上加以判断,并不能从油膜压力的数值上进行准确地分析,因此在分析轴瓦损坏时,有必要求解整个油膜面压力分布。针对某型柴油机连杆大端轴瓦出现异常损坏故障进行了研究,利用轴心轨迹和计算液体动力学（CFD）方法,对轴瓦壁面油压进行了计算分析,结果表明在轴瓦损伤部位存在负压区,从理论上验证了发生穴蚀的可能性。运用轴心轨迹和CFD软件对轴瓦结构进行了改进,改进后使用结果表明,轴瓦运行状态良好,从而进一步证实了本计算方法的可靠性。     

Diffusional titanium alloying of the working surfaces of moving parts

The diffusional titanium alloying of copper-alloy bearing bushes is considered. The dimensions of parts change after saturation as a function of the temperature and the length of the process. The composition of the saturating mixture is presented, along with rational conditions for diffusional titanium surfacing of copper alloys.     

Wear of metal stirring rods in molten aluminium and suspensions of alumina particles in molten aluminium

The wear of stainless steel and titanium stirring rods in molten aluminium and a suspension of alumina particles in molten aluminium was studied. The known characteristic of more rapid wear by stainless steel than titanium was confirmed and the suspension of alumina particles was found to accelerate wear of both metals. Examination of worn specimens revealed that the stainless steel rods were separated from the liquid aluminium by a layer of iron, chromium and aluminium. Wear proceeded by the shedding of projections that formed on the layer into the liquid aluminium. Alumina particles accelerated wear by abrasion of the projections. The titanium was surrounded by a much thinner layer of titanium and aluminium mixture with no projections into the molten aluminium. The distribution of wear around the blades was controlled by the flow of liquid metal and of the alumina particles around each blade.     

卷制轴套模具CAD系统改进

以集成软件UG作为支撑平台,在Visual c++集成开发环境下,利用UG二次开发工具对系统关键功能模块进行了开发,包括产品信息、工艺设计、模具结构设计等模块的开发.采用接口和数据库进行连接,实现系统各模块的相互独立.开发的卷制轴套模具CAD系统软件,具有友好的用户界面、较好的可靠性、维护性、可扩充性以及良好的可移植性和系统容错性.     

Stress-strain state of the surface layer of nitrided bushes in diamond smoothing

The stress-strain state of the nitrided surface layers of bushes in diamond smoothing is simulated. The contact-stress distribution in the nitrided surface layer under the action of the diamond indenter is determined.     

Positioning and Orienting a Drill Axis on a Curved Surface

A novel technique, referred to as a vector setting in the aerospace industry, has been developed for positioning and orienting drilling bushes on curved surfaces. The position and orientation of holes and their axes in parts and tooling in the aerospace industry must conform to strict tolerances; however, the process of locating and orienting the bushes in drilling plates having curved surfaces is slow and time consuming. This is because the existing process used is a trial and error one, and past research in automated drilling in the aerospace industry has not covered this area. A prototype device has been developed which reduces the setting time. The device has two angular adjustments, which are computed using specially written software. The device is used in conjunction with a 3D spatial measurement system in order to determine reference points on the part or tooling and the device. Experimental results on a prototype indicate a substantial time saving as well as good accuracy in orienting the drill axis at a given point on a surface.     

Improving the wear resistance of the cylinder assembly in compact marine diesel engines

The performance of bushes in the 4Ch8.5/11 diesel engine is optimized on the basis of mathematical experiment design. Their wear resistance may be improved by finishing on the basis of special roller burnishing, rather than honing.     

Cavitation erosion—A survey of the literature 1940–1970

The design of a unique rig for the testing of dry running radial bearings under light load is described. Convenient adjustment of all independent parameters and their accurate measurement by electrical methods make the test machine very versatile. Preliminary results about the performances of bushes made of a special, polymer based, composite are presented.     

Precision, limitations, and applications of the ballizing process

Ballizing is a method of burnishing an internal diameter by forcing a precision ground tungsten carbide ball through a slightly undersized pre-machined hole. This paper discusses the precision of the finished hole in terms of dimensional and geometrical tolerances, the limitations of the process, and its potential for sizing small bores, flaring and securing of bushes and other industrial applications     

Synthetic aluminium complex grease: A tribological evaluation using a four‐ball test

This paper describes the preparation and performance evaluation of a synthetic aluminium complex grease. The aluminium complex grease was prepared in situ by reacting stearic acid and benzoic acid in the presence of a synthetic base oil, polyalphaolefin. The preparation of the soap (aluminium benzoate stearate hydroxide) was monitored using Fourier transform infrared. Two different extreme‐pressure additives blended with the prepared aluminium complex grease were evaluated for their extreme‐pressure activity in four‐ball and Timken tests. These greases exhibited higher Timken OK loads (60 lb), lower values of wear‐scar diameter at higher loads, and higher values of weld load in the four‐ball test than the aluminium complex grease without additive. The blended greases were also found to pass rust and corrosion, oxidation‐stability, and shear‐stability tests. The topography of the specimens after four‐ball testing was studied with scanning electron microscopy.