Performance of the Coned-Face End Seal with Regard to Energy Conservation

The effect of a face coning on seal performance, especially energy losses as indicated by a torque, were studied by comparing torque, face temperature, leakage, and wear of a conventional, widely used flat-face seal with three coned-face seals. Experimental evaluation was performed at rotation speeds to 8000 rpm, with pressures to 2758 kPa (400 psig), using a petroleum-base turbine oil. Axial movement of the mating seal parts was recorded using a digital data acquisition system. The height of the convergent-type cone on the face of the tungsten carbide primary ring ranged from 0.51 μm (20 μin) to 5.6 μm (220 μin) over the 3.175-mm to 6.36-mm (0.125-in to 0.25-in) face width. The torque of the coned-face seal, balanced lo 76.3 percent, was an average 42 percent lower, the leakage eleven limes higher than that of the standard flat-face seal. Reducing the balance to 51.3 percent by decreasing the face width of the coned-face seal resulted in lowering the torque by an additional 44 percent and increasing the leakage 12 to 230 times, depending on the seal shaft speed. No measurable wear was observed on the face of the coned seals. All four seals operated in the stable region of the stability map.     

机械密封端面形貌的三维重建及其表征

为了准确方便地描述机械密封端面的三维形貌及泄漏通道,基于密封环端面断层扫描二维图像,研究开发了机械密封端面形貌三维重建程序;提出了机械密封端面形貌的表征参数,并建立了基于体素的密封端面计盒维数和孔隙率算法。研究结果表明：基于断层图像的密封端面三维重建形貌能有效地反映密封端面的三维计盒维数和孔隙率等参数;层与层之间的面孔隙率具有一定的变化规律,在体孔隙率不变的情况下,改变各断层面孔隙率的分布,可以控制动静环密封端面间泄漏通道的形成及泄漏通道的大小;当采样层数较少时,采样层数对计算结果影响较大,在采样层数达到一定数值后,采样层数对计算精度的影响越来越小。     

Membrane blisters: A fixation artifact a study in fixation for scanning electron microscopy

It is been shown by scanning electron microscopy that fixation in glutaraldehyde followed by fixation in osmium tetroxide results in the presence of membrane blisters on the surface of a variety of cells. Fixation in glutaraldehyde alone or osmium tetroxide alone does not result in such extensive artifacts. The blisters, usually 0.2–0.6 μm in diameter, are seen by transmission electron microscopy to be membrane-bound, virtually empty vesicles. It is concluded that the optimum preservation of the cell surface for scanning electron microscopy is provided by fixation in glutaraldehyde alone.     

Experimental Results for a Heat-Sink Mechanical Seal

This work presents experimental results for a heat-sink mechanical seal installed in a 1 × 1.5 × 6 in. ANSI centrifugal water pump. The heat-sink seal is constructed of a stainless steel substrate with an electrodeposited pin fin micro-heat sink located within 3 mm of the end face. Each pin has a ten-sided polygon cross section with a flat-to-flat diameter of 675 μm, a height of 856 μm, and a 300-μm edge-to-edge spacing. The end face is coated with a WC thin film that forms the wear surface for the rotating ring. The heat-sink seal's effectiveness is demonstrated in a significant reduction of both the seal interface and seal chamber temperature when compared to a similar industry standard seal. The heat-sink seal removes 750 W of heat and reduces the stationary ring temperature by 80°C under dead-head conditions using only 1.6 W of coolant pumping power.     

Acoustic imaging of high-temperature superconducting materials

A new method of microstructure examination, acoustic microscopy, was used to study high-temperature superconducting materials. The high-resolution images obtained (up to 0.4 μm resolution) visualize the specimen topography, variations in local acoustic properties, in particular surface and subsurface defects such as cracks, twins, phase and structural discontinuities and film peeling. For bulk specimens a quantitative characteristic was obtained: a local Rayleigh wave velocity (within an area of 10 × 10 μm), which makes it possible, in particular, to characterize individual crystallites in ceramics.     

电化学光整加工中表面毛化的应用

基于对电化学光整加工之后表面微观几何形貌变化的分析,认为“高原”型表面微观几何形貌的存在对电化学光整加工的整平能力及其效果的提高有一定的影响,提出将表面毛化技术应用于电化学光整加工的设想,并实验验证了适度的表面毛化对光整加工是有利的;同时将此方法应用于无缝碳钢钢管内孔的表面光整加工中,在表面粗糙度Ra达0.2μm以下的同时,生产效率也得到提高。     

金属垫片泄漏模型理论研究

依据分形几何理论,结合不可压缩粘性流体层流流动理论,建立基于分形参数的金属垫片泄漏模型,该模型揭示了泄漏率与密封表面形貌之间的关系。研究表明,密封表面分形维数D越大,螺栓-法兰-金属垫片密封系统越不易发生泄漏,这对于法兰和金属垫片密封表面的加工具有重要指导意义。     

晶体已加工表面频率特征对亚表层温度场的影响

为了更加准确地分析表面形貌对KH2PO4(KDP)晶体元件激光损伤和使用性能的影响，通过功率谱密度和连续小波变换对KDP晶体已加工表面存在的实际频率特征进行提取和重构。利用波动光学理论分析经入射波长1.064 μm、功率20 MW/μm2的激光束照射1 ns后，表面频率特征对KDP晶体亚表层光场及温度场的影响。结果表明，当表面频率特征的波长越接近入射光波长1.064 μm，KDP晶体亚表层的光场畸变现象越严重，会造成局部聚焦，温度越高；当波长超过20 μm时，在振幅不变的情况下，最高温度随着波长的增加基本不变。通过切削实验获得的KDP晶体已加工表面上明显存在的波长分别为14 μm、50 μm和140 μm，对KDP晶体亚表层造成的温升分别为56 K、22 K和12 K。当波长相同时，KDP晶体的最高温度与表面频率幅值成线性关系。随着表面频率波长的增加，温度最高点的位置向KDP晶体内部延伸。     

电子束选区熔化成形316L不锈钢的工艺研究

电子束选区熔化是一种利用电子束逐层熔化金属粉末制造三维实体零件的增材制造技术,在航空航天、医学植入体等领域有很好的应用前景。利用316L不锈钢粉末为材料,研究粉末熔化阶段电子束功率恒定、单遍扫描对成形件上表面粗糙度的影响。发现电子束功率P与扫描速度v的比值是影响上表面形貌的关键因素,随着P/v值的增加,上表面形貌由网结状变化为沟壑状,同时粉末材料的飞溅增加。研究上表面形貌随成形高度增加而演变的过程,发现形貌随高度增加不断恶化,并解释了形貌恶化的原因。提出电子束功率递增、多遍扫描的方法,先用低功率电子束使粉末材料熔化聚球但不飞溅,再用大功率电子束使材料重新熔化并充分流动、浸润。这种方法改善了成形件上表面的形貌,表面粗糙度Ra小于8 μm,获得的组织均匀细密,致密度高达99.96%。相对于单遍扫描,多遍扫描不会造成主要元素的额外烧损。     

基于斯特封的往复密封摩擦磨损界面性能实验研究

斯特封是常用的往复密封件,其中斯特封的PTFE圈性能及活塞杆表面材料在往复密封过程中起着重要作用。搭建往复密封实验台,取4组添加碳纤维PTFE的密封圈分别与镀Cr膜活塞杆和镀DLC膜活塞杆进行往复密封台架实验,实验后获取使用过的4组密封圈作为实验样本,并取1个全新未使用的添加碳纤维PTFE的密封圈作为参考样本。通过三维白光干涉表面形貌仪、场发射环境扫描电子显微镜和冷场发射高分辨扫描电子显微镜分别对实验样本的密封唇进行表面形貌、表面磨损和磨损表面元素进行测定。通过实验测定,得出镀膜材料脱落形成磨粒导致密封圈表面磨损。还对密封圈的加工方法和活塞杆镀膜材料的选择提出了建议。     

A Fractal Model of Mechanical Seal Surfaces Based on Accelerating Experiment

The change in surface topography caused by friction and wear influences the wear properties and service life of mechanical seal. To investigate the wear properties of mechanical seals and obtain the variation in surface topography, it is practical to carry out accelerating experiments by increasing the load, speed, or temperature of the medium than safe life tests in the field device. Based on the assumption that the same fractal roughness corresponds to the same wear properties, the pi theorem was introduced to derive the relationship of wear under experimental and actual conditions. By providing detailed values of constants in the pi theorem through accelerating experiments, a fractal model was established to predict the life expectancy of mechanical seals. Under the state of mixed friction, measured values of surface topography for experimental stationary rings and data on a mechanical seal ring's service life in the field device were in accordance with those of the model. The establishment of the fractal model provides conditions for the performance study of long-period operating mechanical seals.     

Tool wear investigation on the precision progressive die for the IC dam-bar cutting process

The IC dam-bar cutting process is conducted with the precision progressive shearing die, while the cutting quality of the sheared product is subject to the wear status of the punch. The main objective of this study was to explore the relationship between the burnished band of the sheared surface and the wear of the shearing punch in the thin sheet cutting process. Firstly, the Taguchi method was applied to scheme the dam-bar cutting experiments. Two different HSS punches, ASP60 and SKH9, were used to punch the simulated leads made of the phosphor bronze C5191R-H. The variance analysis and confirmation experiments were also executed to verify the analytical results. The experimental data was collected to establish the punch wear estimated model. Secondly, a concept of an equivalent wear length of the punch flank was introduced to examine the wear of the punch flank, and the gravimetric wear rate was also calculated to examine the amount of the punch wear due to weight loss. Finally, the estimated model of the gravimetric wear rate through the burnished area of the dam-bar sheared surface was constructed. One can directly determine the status of the cutting punch depending on the size of the burnished band, as a basis for tool changing or regrinding.     

航空作动器主密封结构参数化分析*

航空作动器主密封属于往复密封,在飞机调整姿态时起重要作用。以航空作动器常用的斯特封为例,以摩擦力和反向泵回率作为密封评价指标,通过正向(EHL)和逆向(IHL)求解雷诺方程的方法建立往复密封混合润滑模型,推导往复密封系统的摩擦力和反向泵回率的计算方法。根据理论分析,分别对密封唇口的表面形貌参数、唇口与活塞杆倾角进行结构参数化分析。结果表明:选定的表面均方根粗糙度、唇口与活塞杆倾角均满足反向泵回率大于0,且摩擦力与表面均方根粗糙度、油测倾角成正比,与空气侧倾角成反比。通过分析得到了该型斯特封唇口的最优结构参数,为往复密封圈的结构优化提供了参考依据。     

高强度耐磨铝青铜材料的滚压性能研究

在自行研制的气动滚压装置上,应用响应曲面法中的Box-Bahnken试验设计对高强度耐磨铝青铜材料的滚压性能进行了研究,分别建立了表面粗糙度、显微硬度与滚压参数(滚压力、滚压速度和滚压次数)的数学模型,分析了各参数对表面粗糙度和显微硬度的影响。试验结果表明该滚压装置能使铝青铜工件的表面质量由加工前的Ra2·02μm、HV201达到Ra≤0·12μm、HV330以上。最后根据试验结果对滚压参数进行了优化。     

Investigating the surface quality of the burnished brass C3605—fuzzy rule-based approach

In this work, prediction of burnished surface roughness (R _a) is achieved by using a fuzzy rule-based system. The process state variables used were burnishing speed, feed, and depth. The fuzzy rule-based system has achieved an accuracy of 95.4 % to predict the burnished surface roughness and proved to be convenient in terms of least computational complexity and dealing with nonlinear data such as that obtained in this work.     

基于轮廓法的金刚石线锯整周三维表面形貌测量和评价

针对毫米级尺度线径和微米级尺度磨粒的金刚石线锯整周三维表面形貌测量难以实现与定量评价问题,提出一种基于轮廓法的圆周扫描表面磨粒形貌测量与分析方法。通过显微测量系统沿周向扫描采集金刚石线锯对应的边缘轮廓图像序列,经图像处理后获得金刚石线锯整个圆周表面形貌的坐标点云,采用三次样条插值法对数据进行平滑处理,经圆柱坐标变换处理,可重构金刚石线锯三维表面形貌。在金刚石线锯常用评价参数基础上,提出基于扫描过程二维投影轮廓和三维重构形貌的综合评价参数。采用自行研制的测量系统,对两个规格的线锯（线径外径分别为0.250 mm、0.320 mm;磨粒粒径范围30~40 μm）进行测量和评价。试验结果表明：该方法无需多次拼接,就可完成金刚石线锯整周三维微观形貌测量,并能实现对线锯特征参数的全面评价,可为线锯本身制造及使用过程中的工艺优化提供更加客观的基础数据。     

A Model for Mechanical Seals with Regular Microsurface Structure

A mathematical model is developed to allow performance prediction of all-liquid noncontacting mechanical seals with regular microsurface structure in the form of hemispherical pores. Seal performance such as the equilibrium face separation, friction torque and leakage across the seal are calculated and presented for a range of sealed pressure, pore size and pore ratio of ring surface area. An optimum pore size is found that depends on the other variables and corresponds to maximum axial stiffness and minimum friction torque. Also, a critical pore size is found above which seal failure is possible.     

The tribological behaviors of some rare earth complexes as lubricating additives Part 1. An investigation of the friction-reducing behaviors and an XPS study of the tribochemical characteristics

Several rare earth coordination compounds of 8-hydroxyquinoline and of di-n-hexadecyldithiophosphate were synthesized. The burnished films of these coordination compounds on a GCr15 bearing steel (SAE 52100 steel) disc were prepared. The friction-reducing behaviors of the burnished films were evaluated on a DF-PM friction tester. The friction-reducing behaviors of these complexes as additives in a lithium grease were examined on an SRV fretting wear tester. The binding energies of some typical elements in the complexes before and after friction were determined on an X-ray photoelectron spectrometer. It was found that these coordination compounds could form a quite complete burnished film on a GCr15 bearing steel surface. The lowest friction coefficient was obtained with respect to the burnished film of neodymium di-n-hexadecyldithiophosphate (NdDDP), while a decreased friction coefficient was reached with respect to the burnished film of rare earth 8-hydroxyquinolinate, as compared with the non-burnished friction pairs. Besides, the SRV fretting wear test results revealed that NdDDP in lithium grease exhibited better antiwear and extreme pressure properties than zinc di-n-butyldithiophosphate (ZDDP), while the antiwear and extreme pressure performance of rare earth 8-hydroxyquinolinates is comparable to that of ZDDP. The related results will be published in a following part of this work. The XPS results indicated that tribochemical reactions were involved in the wear process of these coordination compounds as lubricants or as lubricating additives. Here in the first part of this work, the friction-reducing behaviors of the burnished films and of the additives in a lithium grease are dealt with, while the XPS study of the tribochemical characteristics of these complexes is also reported.     

A finite element-based model of normal contact between rough surfaces

Engineering surfaces can be characterized as more or less randomly rough. Contact between engineering surfaces is thus discontinuous and the real area of contact is a small fraction of the nominal contact area. The stiffness of a rough surface layer thus influences the contact state as well as the behavior of the surrounding system. A contact model that takes the properties of engineering surfaces into account has been developed and implemented using finite element software. The results obtained with the model have been verified by comparison with results from an independent numerical method. The results show that the height distribution of the topography has a significant influence on the contact stiffness but that the curvature of the roughness is of minor importance. The contact model that was developed for determining the apparent contact area and the distribution of the mean contact pressure could thus be based on a limited set of height parameters that describe the surface topography. By operating on the calculated apparent pressure distribution with a transformation function that is based on both height and curvature parameters, the real contact area can be estimated when the apparent contact state is known. The model presented is also valid for cases with local plastic flow in the bulk material.     

Stress in the surface layer of objects burnished after milling

This paper presents the effects of modeling the stress in the burnished layer of a complex spatial surface that was previously milled. A spatial kinematic-geometric model of the surface structure after milling is used. This paper presents the results of a numerical experiment on the synergic influence of the technological milling and burnishing parameters responsible for the final state of the geometric structure of a surface on the post-machining stress in the surface layer. The stress in the surface layer plays an important role because it is frequently responsible for the development of cracks, corrosion, and cavitation (in the surface area of injection aluminum molds, press tools, and core cutters). A proper understanding of the mechanisms responsible for the origin and development of residual stress will be conducive to the improvement of functional properties and longer tool life.