硬对偶件表面加工工艺对密封系统性能影响的试验研究

采用试验手段 ,研究了密封系统中硬对偶件表面加工工艺及方法对密封系统性能的影响 ,揭示了这种影响的程度及规律 ,为提高密封系统工作性能提供了新的思路及途径     

微造型在机械密封作用机理研究中若干关键问题的探讨

为探讨端面微造型在机械密封中的作用机理,以形成动压效应的几何楔空间为切入点,分析了端面微造型在摩擦副表面中的几何构成。分析结果表明:端面微造型使摩擦副表面几何形貌不平,并借助压差流和剪切流形成动压效应,而表面微观几何形貌是一种特殊的微造型。实验结果的分析表明,表面微观几何形貌不平可影响动压效应,经电化学光整加工的表面微观几何形貌使润滑膜增厚。机械密封中的摩擦副表面微造型不仅具有润滑与密封的作用,而且还具有速度式泵送与容积式泵送的效应。表面微造型的不平度、分布密度以及形状等因素对润滑膜厚度及其稳定性等影响的研究将有助于机械密封理论和技术的进一步发展。     

包复耐磨密封圈

包复氟塑料橡胶密封圈,系用氟塑料薄膜在橡胶密封圈硫化时,牢固地粘接于橡胶工作表面而成。包复密封圈尤其适用于活动密封。它除了保持橡胶的高弹性特点外,还改变了活动密封工作表面的摩擦对偶,具有摩     

硬同轴线系统装配过程优化

装配过程中出现的连接间隙、密封以及受力状况不佳等问题,直接影响了硬同轴线系统的工作性能。因此,解决硬同轴线系统装配过程中存在的问题,是保证其高可靠性的先决条件。文中通过剖析硬同轴系统的组成,分析故障原因,提出了硬同轴系统装配过程优化工艺方案。通过控制、检验同轴线间隙,划分安装段,设置测试点,监测入射与反射功率,确定补偿垫片尺寸以及安装前调试等手段,提高同轴线系统的工作性能。实践表明,这些方法具有较好的可操作性和较高的实用价值,优化了装配过程,提高了硬同轴线系统的可靠性。     

端面密封材料S-07不锈钢滑动摩擦学行为的分子动力学模拟

为探究端面密封材料S-07不锈钢在不同参数下的摩擦学行为,构建纳米尺度下S-07不锈钢的摩擦磨损模型,以对偶件的压入深度和滑动速度作为变量,研究S-07不锈钢表面摩擦学性能及形貌变化。结果表明：随着摩擦相对滑动速度的增加(50、100、150 m/s),S-07不锈钢磨损表面粗糙度降低;随着对偶件压入深度(0.3、0.6、0.9 nm)的增大,摩擦因数呈上升趋势;磨损量随压入深度增大而增大,随滑动速度上升呈下降趋势。在微观尺度上,从位错、塑性变形等角度解释了在不同磨损条件下S-07不锈钢性能变化的原因,为该材料适用摩擦工况的选择提供了理论参考。     

对偶件表面微结构取向对PTFE基自润滑轴承材料摩擦性能的影响

研究了聚四氟乙烯(PTFE)基自润滑轴承材料与45#钢对摩时,对偶件45#钢表面微结构取向对PTFE基自润滑轴承材料摩擦学性能及转移膜的影响。结果表明:对偶件表面微结构取向与摩擦方向的夹角为0°和90°时,形成的转移膜较为均匀,且磨损量较小;夹角45°时,形成的转移膜不完整,且磨损较大。     

常见粗糙度缺陷的原因分析与排除

表面粗糙度是指零件表面的微观几何形状误差,是零件表面质量的重要技术指标。它不仅影响美观,而且对零件接触面的摩擦、运动面的磨损、贴合面的密封、配合面的可靠、旋转件的疲劳强度以及抗腐蚀性能等都有影响。设计每一个零件时,都是按照使用要求规定其表面粗糙度等级的,所以     

高分子材料在活门中的密封比压

活门作为气动液压系统的控制元件,在液体火箭的弹体、发动机和伺服机构中应用十分广泛。在保证活门密封的可靠性中,密封面密封比压具有重要意义。它的大小直接反映出活门的密封性能和技术特点,因此测量出密封比压与介质压力、活门座宽度、密封材料力学性能之间的关系,是延长活门使用寿命,提高密封可靠性的根本途径。一、密封原理和比压活门密封是由关闭件和活门座接触表面上产生的密封力来实现的,而密封力是预紧     

复合填充改性聚酰亚胺润滑材料的摩擦学性能

采用M-2000型摩擦磨损试验机考察纳米碳酸钙和石墨复合填充聚酰亚胺(PI)润滑材料在不同速度和载荷下与GCr15轴承钢对摩时的摩擦磨损性能,并利用扫描电子显微镜分析PI材料及其对偶件磨损表面形貌。结果表明,单独填充纳米CaCO_3时,聚酰亚胺摩擦因数轻微减小,体积磨损率显著增大,而单独填充石墨后,聚酰亚胺摩擦学性能有显著的改善;纳米CaCO_3和石墨复合填充后,二者存在协同效应,减摩抗磨能力显著提高;PI材料的摩擦学性能与对偶钢环表面转移膜的性质紧密相关,纳米CaCO_3能显著增强转移膜与对偶件的结合强度。     

复合填充改性聚酰亚胺润滑材料的摩擦学性能研究

采用M-2000 型摩擦磨损试验机考察纳米碳酸钙和石墨复合填充聚酰亚胺(PI) 润滑材料在不同速度和载荷下与GCr15 轴承钢对摩时的摩擦磨损性能,并利用扫描电子显微镜分析PI 材料及其对偶件磨损表面形貌。结果表明,单独填充纳米CaCO3时,聚酰亚胺摩擦因数轻微减小,体积磨损率显著增大,而单独填充石墨后,聚酰亚胺摩擦学性能有显著的改善;纳米CaCO3和石墨复合填充后,二者存在协同效应,减摩抗磨能力显著提高;PI材料的摩擦学性能与对偶钢环表面转移膜的性质紧密相关,纳米CaCO3能显著增强转移膜与对偶件的结合强度。     

表面波度对液体椭圆孔端面密封上游泵送特性的影响

表面波度与端面几何型槽的耦合影响使得密封性能的变化规律更为复杂。基于粗糙和波度表面假设,建立空化效应下端面椭圆孔液体上游泵送密封的理论分析模型,对上游泵送端面密封的压力分布和泄漏率进行数值求解计算,分析周向表面波度幅值、数量等几何参数和转速、密封压力等操作参数对开启力和泄漏率的影响规律。结果显示：表面波度使得密封端面产生更高的流体动压效果,并减弱上游泵送效果,容易导致密封介质的泄漏;随着波高和周向波数的增加,开启力略有增加;泄漏率随着波高的增加呈现正向增强趋势,但波数对泄漏率没有明显影响;在空化效应和表面波度的影响下,速度剪切产生的密封端面开启力可增加50%以上,并形成流体的完全上游泵送;密封压力和膜厚的增加,使得流体的上游泵送性能和密封性下降。     

Theoretical study of solid back-up rings for elastomeric seals in hydraulic actuators

The use of back-up rings to support elastomeric seals in high-pressure hydraulic systems is well established in the industry. However, little is known about the operation of such devices and how they affect or interfere in the sealing mechanism of the seals they accompany. This study is an attempt to model solid, soft back-up rings in terms of elastohydrodynamic lubrication and establish their exact role in a sealing system in terms of sealing performance (leakage). The model is applied on a typical case of a linear hydraulic actuator for a wide range of sealed pressures (1–35 MPa) and operating temperatures (−55 to +135 °C), and with one ring installed on the low-pressure side of the actuator. A system of a rubber seal and a properly selected and installed back-up ring is shown to be often significantly more efficient in terms of fluid leakage than the seal without the back-up ring. A study reveals the effect of various parameters of the ring (e.g. the elastic modulus and the surface roughness) on the sealing mechanism and shows the optimum selection to minimize leakage.     

Effect of Surface Characteristics on Compressive Stress and Leakage Rate in Gasketed Flanged Joints

The effect of surface characteristics on compressive stress and leakage rate in gasketed flanged joints is discussed qualitatively and quantitatively based on experimental verifications. The sensitivity of the sealing phenomenon to the sealing surface characteristics, gas pressure and stress level is presented. Sealing surfaces produced with grinding, turning and milling procedures of different roughness values were the subject of the tests with three types of gasket, namely, PTFE (polytetrafluoroethylene), graphite, and spiral wound. The experimental results indicated that the roughness value Ra (average arithmetic height) has no effect on the sealing performance of the gasket, except for the ground type sealing surfaces. The platen (flange) surface forms were found to be the determining factor on the leakage rate and flow regime for gasketed flanged joints. It is shown that the surface characteristics have no effect on the leakage rate and on the gasket performance for the PTFE gasket at high stress levels. However, at low stress levels the rougher ground and milled sealing surfaces having radial channels on the surface produce larger leakage rates. The effect of surface characteristics, stress level, and gas pressure was more evident on the graphite and spiral wound gasket types, at both low and high stress levels. It is also shown that the leakage rate follows an exponential law as a factor of surface stress and gas pressure, for all sealing surface characteristics and gasket types. While there is little difference in the leakage rate for the PTFE gasket when the gasket stress level is increased by a factor of two, from S3 to S5, a substantial leakage rate reduction by a ratio of 17.5 times was observed for the graphite and spiral wound gaskets for most sealing surfaces. On the other hand, when increasing the helium gas pressure from 200 to 800 p.s.i., the leakage rate increased by 5 times for the PTFE, and up to10 times for the graphite and the spiral wound gaskets. It was determined that while molecular flow regimes can be achieved for the PTFE gasket for all sealing surfaces, the two other gasket types provided laminar flow under the same operating conditions.     

Improving the Anti-seizure Ability of SiC Seal in Water with RIE Texturing

The demand for higher pressure and higher speed of sealing systems is currently increasing due to stricter standards for permissible emissions. Silicon carbide (SiC) is thought to be a promising material for sealing systems operating in water, since the combination of SiC and water is both environmentally friendly and energy saving. The purpose of this study is to improve the anti-seizure ability of SiC seals working in water by means of surface texturing. The texture pattern of micro-pits evenly distributed in a square array is formed on one of the contact surfaces by reactive ion etching (RIE). Experiments which simulate the working condition of mechanical seals were carried out to evaluate the effect of micro-pits on the critical seizure load. It is found that micro-pit texturing is an effective way to stabilize friction, to reduce the friction coefficient, and to expand the low-friction range ( < 0.05) of SiC seals working in water.     

质子交换膜燃料电池密封系统热力耦合仿真研究

温度影响质子交换膜燃料电池（PEMFC）的密封性能和力学行为,因而影响其使用寿命和可靠性。为研究PEMFC在热力耦合下的密封性能和力学行为,建立PEMFC单电池和多电池结构的二维模型,研究密封系统在不同工作温度下的应力-应变分布,讨论橡胶密封圈压缩比、双极板错位和密封垫尺寸对PEMFC密封性能和力学性能的影响。结果表明：温度对密封圈的Mises应力和膜电极组件（MEA）框架接触压力有很大影响;在不同工作温度下单电池和多电池结构的密封性能相似,应力和接触压力分布差别也不大,因此单电池结构的研究结论可以推广到多电池结构;随着橡胶密封圈压缩比和密封圈尺寸的增加,燃料电池密封性能得到改善;而双极板错位会加剧MEA框架的变形;高应力区出现在橡胶密封圈的横截面内部,容易导致局部应力集中和密封失效。     

Prediction of Gasket Leakage Rate and Sealing Performance Through Fuzzy Logic

Leakage rate prediction and control are of the utmost importance in most industrial applications for gasketed flanged joints in high-pressure systems, for safety and environmental reasons. In addition, loss of media, and damage to the plant, resulting from leaky joints can be very costly for the industries. Gasket testing and the evaluation of their sealing performance are complex, time-consuming, and costly, and require sophisticated tools capable of predicting leakage based on limited data. In the present work, fuzzy logic is used as a tool to predict the leakage rate and gasket performance of gasketed flanged joints. Different fuzzy models are developed and validated with experimental results for given operating conditions, taking into consideration the gasket type and surface roughness of the mating faces. It is shown that limited experimental test data can be used to build fuzzy models that predict gasket leakage rate and sealing performance.     

平面型非金属阀瓣截止阀的密封性能

应用有限元分析软件建立平面型非金属阀瓣截止阀密封副的简化模型,对变操作工况下密封副的接触应力分布和变形情况进行分析。对比相同工况下不同结构阀瓣的接触应力分布和位移变化的差异,比较其性能,并采用试验进行验证。结果表明:密封接触面上应力分布关于密封面中径呈对称分布,在接触面内外径处应力最大,并从两端向密封面中径方向减小。阀瓣结构中,密封垫径向有约束的阀瓣较密封垫径向无约束的阀瓣密封性能好。     

三偏心蝶阀密封面在位测量的点云数据处理方法

三偏心蝶阀依靠蝶板和阀座密封面的充分面接触实现零泄漏的密封效果,而密封面的加工制造精度对密封性能有着至 关重要的作用。 现有的密封面测量主要依赖离线测量的方式,存在着测量基准不统一、二次装夹造成的测量误差等问题。 本文 提出了密封面精密在位测量技术以及原始点云数据处理方法。 针对被测密封面,提出波谷-聚类算法和考虑约束条件的法矢- 曲面拟合算法,得出密封面的关键参数和加工误差。 该算法较最小二乘法等算法在相对求解精度上提高了 60% 以上。 现场在 位测量的三偏心蝶阀密封面锥角与三坐标仪测量结果的相对误差仅为 0. 43% ,满足测量相对误差±0. 5% 的要求,密封面在位测 量技术的测量精度得到了有效验证,为今后高端阀门的精密测量提供了可靠的技术手段。     

基于多孔介质理论的双粗糙面金属静密封泄漏模型

粗糙面微观几何形貌是影响静密封泄漏特性的重要因素。应用粗糙面的三维点云数据,将粗糙面进行离散化处理,进而将由双粗糙面构成的密封界面等效为三维逾渗栅格模型,基于多孔介质理论计算得到密封界面的孔隙率和渗透率,从而建立了一种双粗糙密封界面的泄漏率模型。搭建金属静密封泄漏率测量试验台,通过对环面金属静密封泄漏特性的试验研究,验证了该泄漏模型的有效性。利用该模型分析了表面纹理方向、粗糙面波动频率与材料特性对金属静密封泄漏特性的影响。结果表明：各向异性粗糙面构成的密封界面具有较好的密封性能;粗糙面波动频率越大,密封性能越好;低硬度材料易于实现有效密封;在重载情况下,粗糙面微观几何形貌对孔隙率与泄漏率的影响不显著。