柔性石墨/编织盘根组合填料密封性能试验研究

在新型填料密封和摩擦学性能试验机上,进行柔性石墨/编织盘根组合填料的往复运动试验,考察填料的密封性能和摩擦学性能,考察轴向应力、石墨环截面形状和密度对组合填料密封性能和摩擦学性能的影响。结果表明:随着轴向应力的增加,组合填料的泄漏率有所下降,但摩擦力会显著上升,填料的磨损加剧、密封寿命大大缩短;优化柔性石墨环的截面形状能改善组合填料的综合性能,V型石墨环填料的密封性能和摩擦学性能均明显优于平口石墨环;柔性石墨环的密度对组合填料的密封性能和摩擦学性能也有重要影响,具有密度梯度的石墨环组合填料性能优于等密度石墨环填料。对于等密度的石墨环组合填料,推荐使用密度为1.5 g/cm3左右。     

新版《柔性石墨填料环 试验方法》标准修订解读

柔性石墨填料环作为目前相对应用较广泛，密封性能优异，耐酸碱腐蚀的填料密封器件，相对其他种类的填料密封，耐高温工况能力强，是目前国内机械装备密封中十分关键和不可替代的组成部分。2022年发布的GB/T 29035-2022《柔性石墨填料环试验方法》国家标准修订项目，在原标准的基础上对热失重、摩擦磨损和试样规格等技术参数进行了调整，并增加了硫含量测定方法。标准主要内容和技术指标均已确定并经过试验验证。为增进企业对该标准的理解，该文对标准的主要内容、试验验证步骤进行了梳理，便于企业参照使用本标准，提高对应产品的质量。     

柔性石墨密封件

经处理过的碳化合物和石墨用作动密封已经很久了,处理过的碳用作密封圈、滑环、填料圈或防护环,而处理过的石墨粉和碳纤维用作软质填料的辅助材料。但长期以来处理过的碳和石墨却未能在静密封领域里应用。最近得到了一种新的纯石墨结构材料,它不仅适用于动密封,而且也适用于静密封,至此困难的密封问题就被解决了。这种结构材料是西德Sigri制造的,商业上名称为Sigraflex,其产品有柔性石墨带、积层薄片和其他用压力成形的圈。制造制造这种新石墨产品的原材料是纯净的,适当地定过向的石墨,通过化学和热处理方法使晶间距离增大到其标准值3.35 A°的数倍。     

核电阀门密封材料研究与填料的结构设计

通过对一种高强度、高纯度,能耐化学腐蚀以及适应高温深冷,并符合核电累积辐照剂量要求的非金属密封材料柔性石墨的研究。探讨柔性石墨填料的各项化学元素和物理机械性能,用以满足核电阀门密封的适用规范;采用新颖的结构设计,以提高柔性石墨填料在核电阀门上的密封性能;开发出一种适用于AP1000或压水堆核电厂的阀门密封填料,并加以科学验证其在应用中的优异表现。     

柔性石墨密封(下)

柔性石墨密封件主要用于填料密封和垫片密封,表3列出了国产主要柔性石墨品种。表列之外,还有各种柔性石墨-金属复合垫片等。安装技术分填料密封和垫片密封两部分叙述。.压盖填料密封压盖填料密封是最原始、最简单的密封方法,阀杆密封、搅拌器轴封、叶片式、容积式泵以及真空泵的大部、汽锤密封、热交换器填料密封、氨压缩机密封等均可采用压盖填料密封。     

柔性石墨材料的特性及其应用

柔性石墨材料是一种新颖的纯石墨材料,制造工艺已发表在本刊79年第2期。由于柔性石墨是纯石墨材料,所以它具有普通石墨所具有的特性如耐热性、耐腐蚀性、耐辐照性及自润滑性等。又因为柔性石墨是经过特殊处理的石墨,所以它还具有普通石墨所没有的独特的柔软性与弹性。近年来,柔性石墨材料已广泛地用作泵、阀等的填料及垫片,其他方面的用途正处于逐步开展阶段,如作为热处理用的真空炉内衬及动力工程发动机汽缸密封等。本文着重介绍柔性石墨材料的性能及某些应用。     

阀用柔性石墨成组填料动态密封性能的试验研究

在模拟阀杆工作的条件下,对阀用柔性石墨成组填料的泄漏率和使用寿命进行了试验,显示出该成组填料比传统矩形截面组合填料的密封性能好、使用寿命长,是一种对环境友好、具有广泛应用前景的新型密封填料。     

柔性石墨填料在动密封上的试验与应用

我厂1979年起把柔性石墨使用在KBH-55-180离心泵透平热泵上,经过反复试验,取代了传统的锡泊包石棉绳填料(简称锡纸填料)。运行五年,该密封性能稳定,泄漏量少,取得了良好的密封效果。一、应用柔性石墨的分析柔性石墨应用在我厂高温高压离心透平泵上,从技术上分析是可行的,它具备了以下五个主要条件: 1.耐温性能好。柔性石墨在非氧化介质     

柔性石墨垫片在大直径搪瓷塔法兰上的应用

我厂氯苯吸附塔为钢壳内衬搪瓷,直径1米,高5米,由两个塔节和上下封头组成。塔节、封头为法兰连接,日本设计采用四氟包石棉垫片密封。由于搪瓷烧结过程中不可避免的变形,故塔节法兰面的平面度很差,一般在3/1000左右。因此,要求密封垫片具有足够的压缩率和回弹率,还要求密封垫片同搪瓷釜(塔)一样满足耐压、耐温、耐腐蚀的条件。 柔性石墨具有耐温变、耐腐蚀、耐辐射等性能及良好的弹性、柔性、自润滑性、不渗透性和化学稳定性,在石油、化工等工业中有着广泛的适用性。它以及由它派生出来的石墨缠绕垫片、石墨编织盘根、石墨填料环等产品正在取代四氟、橡胶和石棉制品。 1989年,我厂与滨州石墨密封件厂合作,将厚为6mm的垫片装机试用。一年来,有效地起到了密封作用,证明大型塔罐使用柔性石墨垫片是完全可行的。     

柔性石墨产品在海宁开发成功

海宁市密封材料厂开发的柔性石墨编织填料、柔性石墨填料环 ,柔性石墨金属缠线垫片等系列产品 ,最近在合肥通过了机械部有关部门组织的技术鉴定。密封材料由过去的石棉制品过渡到现在的石墨材料 ,是国际上的发展趋势 ,而在我国目前还处在试行阶段。海宁密封材料厂引进清华大学的专利技术 ,采用国内最先进的电化学方法生产的柔性石墨系列产品 ,各项技术指标在国内尚属一流 ,可广泛用于压力泵 ,管道类工业设施以及航空、航天、石化、冶金、发电等行业 ,还可用于汽车发动机的汽缸垫圈柔性石墨产品在海宁开发成功@孙福     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.